ZIP codes and county lines in Michigan

343 of the 993 ZIP code areas in Michigan, or 34.5%, overlap more than one county. If your territories, tax rules or service areas are set by county and your list is by ZIP, these are the rows where the two disagree.

ZIP code areas: 993
In more than one county: 343
At least 5% in a second county: 253
Cross a state line: 1

How Michigan compares

Michigan ranks 24 of 52 (the 50 states, DC and Puerto Rico) by the share of its ZIP code areas that overlap more than one county. 83 of its counties have at least one split ZIP code area along an edge. 1 of its ZIP code areas also reach into Wisconsin, so a ZIP list that is meant to stop at the state line does not.

Counties with the most split ZIP code areas

Kent County: 21 ZIP codes shared with another county
Genesee County: 20 ZIP codes shared with another county
Newaygo County: 19 ZIP codes shared with another county
Montcalm County: 18 ZIP codes shared with another county
Ottawa County: 18 ZIP codes shared with another county

Every split ZIP code area in Michigan

Each row is one ZCTA and the counties its land falls in, largest share first. Counties in another state are marked with that state. Sort by the share outside the main county to put the most evenly divided ones first.

	Share of land by county
48014	St. Clair County 96.2% Lapeer County 3.8%	3.8%	2
48032	St. Clair County 80.5% Sanilac County 19.5%	19.5%	2
48041	St. Clair County 96.8% Macomb County 3.2%	3.2%	2
48097	St. Clair County 77.6% Sanilac County 22.4%	22.4%	2
48111	Wayne County 97.2% Washtenaw County 2.1% Monroe County 0.6%	2.8%	3
48117	Monroe County 99.4% Wayne County 0.6%	0.6%	2
48134	Wayne County 84.8% Monroe County 15.2%	15.2%	2
48137	Livingston County 74.6% Washtenaw County 25.4%	25.4%	2
48158	Washtenaw County 98.5% Jackson County 1.4%	1.4%	2
48160	Monroe County 51.9% Washtenaw County 48.1%	48.1%	2
48164	Wayne County 96.3% Monroe County 3.7%	3.7%	2
48167	Oakland County 45.7% Wayne County 29.8% Washtenaw County 24.5%	54.3%	3
48168	Wayne County 54.6% Washtenaw County 45.4%	45.4%	2
48169	Livingston County 94.8% Washtenaw County 5.2%	5.2%	2
48170	Wayne County 54.7% Washtenaw County 45.3%	45.3%	2
48176	Washtenaw County 99.6% Lenawee County 0.4%	0.4%	2
48178	Oakland County 36.5% Washtenaw County 34.2% Livingston County 29.3%	63.5%	3
48189	Washtenaw County 69.5% Livingston County 30.5%	30.5%	2
48191	Washtenaw County 87.7% Monroe County 12.3%	12.3%	2
48236	Wayne County 97.4% Macomb County 2.6%	2.6%	2
48306	Oakland County 98.1% Macomb County 1.9%	1.9%	2
48371	Oakland County 88.0% Lapeer County 12.0%	12.0%	2
48380	Oakland County 60.9% Livingston County 39.1%	39.1%	2
48415	Saginaw County 95.2% Tuscola County 2.9% Genesee County 1.9%	4.8%	3
48416	Sanilac County 54.0% Lapeer County 40.0% St. Clair County 5.9%	46.0%	3
48418	Shiawassee County 66.2% Genesee County 24.8% Livingston County 9.1%	33.9%	3
48420	Genesee County 96.2% Tuscola County 3.3% Saginaw County 0.5%	3.8%	3
48421	Lapeer County 95.0% Genesee County 5.0%	5.0%	2
48423	Genesee County 98.8% Lapeer County 1.3%	1.3%	2
48428	Lapeer County 98.7% Oakland County 1.3%	1.3%	2
48429	Shiawassee County 96.8% Genesee County 3.2%	3.2%	2
48430	Livingston County 67.7% Genesee County 22.4% Oakland County 9.9%	32.3%	3
48433	Genesee County 96.2% Shiawassee County 3.9%	3.9%	2
48435	Tuscola County 50.0% Lapeer County 50.0%	50.0%	2
48436	Genesee County 90.5% Shiawassee County 9.5%	9.5%	2
48438	Genesee County 71.5% Lapeer County 28.5%	28.5%	2
48439	Genesee County 98.7% Oakland County 1.3%	1.3%	2
48441	Huron County 98.2% Sanilac County 1.8%	1.8%	2
48442	Oakland County 95.9% Genesee County 2.9% Livingston County 1.1%	4.1%	3
48444	Lapeer County 93.5% St. Clair County 6.5%	6.5%	2
48449	Shiawassee County 72.7% Genesee County 27.3%	27.3%	2
48451	Genesee County 73.7% Livingston County 26.3%	26.3%	2
48453	Sanilac County 82.9% Lapeer County 11.6% Tuscola County 5.5%	17.1%	3
48456	Sanilac County 79.8% Huron County 20.2%	20.2%	2
48457	Genesee County 72.8% Saginaw County 27.2%	27.2%	2
48460	Shiawassee County 59.6% Saginaw County 40.1% Genesee County 0.3%	40.4%	3
48462	Oakland County 91.1% Lapeer County 8.4% Genesee County 0.4%	8.9%	3
48463	Genesee County 99.8% Lapeer County 0.2%	0.2%	2
48464	Lapeer County 80.6% Tuscola County 12.3% Genesee County 7.1%	19.4%	3
48470	Huron County 99.5% Sanilac County 0.5%	0.5%	2
48475	Sanilac County 54.0% Huron County 46.0%	46.0%	2
48604	Saginaw County 96.0% Bay County 4.0%	4.0%	2
48610	Gladwin County 48.5% Arenac County 26.1% Ogemaw County 25.4%	51.5%	3
48612	Gladwin County 96.5% Clare County 2.4% Midland County 1.2%	3.5%	3
48613	Bay County 58.5% Gladwin County 41.5%	41.5%	2
48614	Saginaw County 95.0% Gratiot County 5.0%	5.0%	2
48615	Gratiot County 67.9% Midland County 32.1%	32.1%	2
48616	Saginaw County 98.3% Shiawassee County 1.7%	1.7%	2
48617	Clare County 64.8% Isabella County 35.2%	35.2%	2
48618	Midland County 76.5% Isabella County 21.4% Gladwin County 2.1%	23.5%	3
48619	Oscoda County 81.3% Montmorency County 18.7%	18.7%	2
48622	Clare County 63.5% Isabella County 36.5%	36.5%	2
48623	Saginaw County 63.6% Midland County 24.1% Bay County 12.3%	36.4%	3
48624	Gladwin County 76.5% Roscommon County 12.1% Clare County 10.3% Ogemaw County 1.1%	23.5%	4
48626	Saginaw County 87.8% Midland County 12.2%	12.2%	2
48628	Midland County 90.8% Gladwin County 9.2%	9.2%	2
48629	Roscommon County 99.9% Missaukee County 0.1%	0.1%	2
48632	Clare County 63.3% Isabella County 31.8% Osceola County 4.6% Mecosta County 0.4%	36.7%	4
48637	Saginaw County 68.9% Midland County 18.9% Gratiot County 12.2%	31.1%	3
48642	Midland County 84.0% Bay County 16.0%	16.0%	2
48647	Oscoda County 97.1% Alcona County 2.9%	2.9%	2
48649	Saginaw County 94.2% Shiawassee County 5.8%	5.8%	2
48650	Bay County 93.5% Arenac County 6.5%	6.5%	2
48652	Gladwin County 55.3% Bay County 22.8% Midland County 21.8%	44.7%	3
48653	Roscommon County 58.3% Crawford County 41.7%	41.7%	2
48654	Ogemaw County 76.9% Oscoda County 23.1%	23.1%	2
48658	Arenac County 89.5% Bay County 10.5%	10.5%	2
48659	Arenac County 97.9% Bay County 2.1%	2.1%	2
48662	Gratiot County 78.3% Midland County 21.7%	21.7%	2
48708	Bay County 93.7% Saginaw County 6.3%	6.3%	2
48726	Tuscola County 64.6% Sanilac County 26.4% Huron County 9.1%	35.4%	3
48727	Lapeer County 73.6% Tuscola County 26.4%	26.4%	2
48728	Alcona County 88.0% Oscoda County 12.0%	12.0%	2
48734	Saginaw County 89.7% Tuscola County 10.3%	10.3%	2
48735	Tuscola County 53.3% Huron County 46.7%	46.7%	2
48737	Alcona County 72.7% Iosco County 27.3%	27.3%	2
48738	Alcona County 97.5% Iosco County 2.5%	2.5%	2
48739	Iosco County 71.8% Ogemaw County 28.2%	28.2%	2
48744	Tuscola County 84.0% Lapeer County 16.0%	16.0%	2
48745	Alcona County 97.3% Iosco County 2.7%	2.7%	2
48746	Tuscola County 89.4% Genesee County 10.6%	10.6%	2
48747	Bay County 96.1% Saginaw County 3.9%	3.9%	2
48750	Iosco County 96.8% Alcona County 3.2%	3.2%	2
48756	Ogemaw County 99.7% Arenac County 0.3%	0.3%	2
48757	Tuscola County 66.5% Saginaw County 26.1% Bay County 7.4%	33.5%	3
48759	Huron County 99.1% Tuscola County 0.9%	0.9%	2
48760	Lapeer County 54.0% Tuscola County 46.0%	46.0%	2
48761	Ogemaw County 35.6% Alcona County 30.6% Oscoda County 17.7% Iosco County 16.2%	64.4%	4
48762	Alcona County 87.7% Alpena County 12.3%	12.3%	2
48763	Iosco County 92.8% Arenac County 7.2%	7.2%	2
48765	Arenac County 59.7% Iosco County 40.3%	40.3%	2
48767	Tuscola County 96.9% Huron County 3.1%	3.1%	2
48770	Iosco County 99.4% Ogemaw County 0.6%	0.6%	2
48807	Gratiot County 79.8% Saginaw County 20.2%	20.2%	2
48809	Ionia County 77.9% Kent County 20.2% Montcalm County 1.9%	22.1%	3
48811	Montcalm County 63.0% Gratiot County 37.0%	37.0%	2
48813	Eaton County 99.9% Calhoun County 0.1%	0.1%	2
48815	Ionia County 98.0% Kent County 1.9%	1.9%	2
48821	Eaton County 95.7% Ingham County 4.3%	4.3%	2
48823	Ingham County 57.5% Clinton County 42.5%	42.5%	2
48827	Eaton County 82.3% Ingham County 15.8% Jackson County 1.9%	17.7%	3
48829	Montcalm County 96.2% Isabella County 3.8%	3.8%	2
48831	Clinton County 44.5% Shiawassee County 33.1% Saginaw County 20.5% Gratiot County 1.9%	55.5%	4
48834	Montcalm County 66.9% Ionia County 33.1%	33.1%	2
48837	Eaton County 71.6% Clinton County 24.0% Ionia County 4.4%	28.4%	3
48838	Montcalm County 78.2% Kent County 20.4% Ionia County 1.4%	21.8%	3
48840	Ingham County 61.0% Shiawassee County 20.3% Clinton County 18.7%	39.0%	3
48841	Shiawassee County 79.4% Saginaw County 20.6%	20.6%	2
48842	Ingham County 98.3% Eaton County 1.7%	1.7%	2
48845	Ionia County 43.3% Clinton County 29.7% Montcalm County 18.4% Gratiot County 8.6%	56.7%	4
48848	Shiawassee County 60.2% Clinton County 39.8%	39.8%	2
48849	Ionia County 77.6% Barry County 17.6% Eaton County 4.8%	22.4%	3
48850	Montcalm County 66.7% Mecosta County 33.3%	33.3%	2
48858	Isabella County 98.6% Midland County 1.4%	1.4%	2
48861	Eaton County 91.6% Ionia County 8.4%	8.4%	2
48866	Clinton County 55.5% Shiawassee County 44.5%	44.5%	2
48872	Shiawassee County 79.8% Ingham County 16.4% Livingston County 3.8%	20.1%	3
48873	Ionia County 50.3% Clinton County 49.8%	49.8%	2
48875	Ionia County 90.0% Clinton County 10.0%	10.0%	2
48877	Gratiot County 45.7% Montcalm County 41.5% Isabella County 12.8%	54.3%	3
48879	Clinton County 96.2% Gratiot County 3.8%	3.8%	2
48880	Gratiot County 54.0% Midland County 38.1% Isabella County 7.9%	46.0%	3
48883	Isabella County 65.0% Midland County 34.7% Gratiot County 0.3%	35.0%	3
48886	Montcalm County 95.5% Mecosta County 4.5%	4.5%	2
48889	Gratiot County 98.5% Montcalm County 1.5%	1.5%	2
48890	Eaton County 53.4% Ionia County 46.6%	46.6%	2
48892	Ingham County 79.4% Livingston County 20.6%	20.6%	2
48894	Clinton County 86.3% Ionia County 13.7%	13.7%	2
48897	Barry County 97.6% Eaton County 2.4%	2.4%	2
48906	Clinton County 77.7% Ingham County 16.9% Eaton County 5.4%	22.3%	3
48911	Ingham County 80.3% Eaton County 19.7%	19.7%	2
48917	Eaton County 86.9% Ingham County 13.1%	13.1%	2
49009	Kalamazoo County 95.9% Van Buren County 4.1%	4.1%	2
49010	Allegan County 99.0% Van Buren County 1.0%	1.0%	2
49011	Calhoun County 89.5% Branch County 8.9% St. Joseph County 1.6%	10.5%	3
49012	Kalamazoo County 98.3% Calhoun County 1.7%	1.7%	2
49015	Calhoun County 99.9% Kalamazoo County 0.1%	0.1%	2
49017	Calhoun County 77.2% Barry County 22.8%	22.8%	2
49021	Eaton County 46.0% Barry County 39.1% Calhoun County 14.9%	54.0%	3
49022	Berrien County 97.8% Van Buren County 2.2%	2.2%	2
49026	Van Buren County 88.8% Allegan County 11.2%	11.2%	2
49030	St. Joseph County 86.4% Branch County 13.6%	13.6%	2
49034	Kalamazoo County 79.2% Calhoun County 20.8%	20.8%	2
49038	Berrien County 86.3% Van Buren County 13.7%	13.7%	2
49040	St. Joseph County 73.0% Branch County 27.0%	27.0%	2
49042	St. Joseph County 91.9% Cass County 8.1%	8.1%	2
49045	Van Buren County 80.2% Cass County 19.8%	19.8%	2
49047	Cass County 90.6% Van Buren County 7.5% Berrien County 1.9%	9.4%	3
49052	Kalamazoo County 77.2% Calhoun County 22.8%	22.8%	2
49055	Van Buren County 93.2% Allegan County 6.8%	6.8%	2
49056	Van Buren County 63.3% Allegan County 36.8%	36.8%	2
49060	Barry County 76.4% Kalamazoo County 23.6%	23.6%	2
49065	Van Buren County 98.7% Kalamazoo County 1.3%	1.3%	2
49067	Cass County 63.5% St. Joseph County 29.1% Van Buren County 7.4%	36.5%	3
49071	Van Buren County 76.0% Kalamazoo County 24.0%	24.0%	2
49072	St. Joseph County 96.3% Kalamazoo County 3.8%	3.8%	2
49073	Barry County 84.6% Eaton County 15.4%	15.4%	2
49076	Eaton County 54.3% Calhoun County 45.7%	45.7%	2
49078	Allegan County 84.8% Kalamazoo County 12.2% Van Buren County 3.1%	15.2%	3
49080	Allegan County 53.0% Barry County 30.6% Kalamazoo County 16.4%	47.0%	3
49082	Branch County 92.6% Hillsdale County 7.4%	7.4%	2
49087	Kalamazoo County 95.2% Van Buren County 4.8%	4.8%	2
49090	Van Buren County 59.0% Allegan County 41.0%	41.0%	2
49092	Calhoun County 72.1% Branch County 27.9%	27.9%	2
49093	St. Joseph County 94.7% Cass County 5.3%	5.3%	2
49094	Branch County 77.5% Calhoun County 22.5%	22.5%	2
49097	Kalamazoo County 94.7% St. Joseph County 5.3%	5.3%	2
49098	Berrien County 76.4% Van Buren County 23.6%	23.6%	2
49099	St. Joseph County 81.6% Cass County 18.4%	18.4%	2
49102	Berrien County 95.6% Cass County 4.4%	4.4%	2
49111	Berrien County 97.6% Cass County 2.4%	2.4%	2
49120	Berrien County 53.0% Cass County 47.0%	47.0%	2
49220	Lenawee County 71.6% Hillsdale County 28.4%	28.4%	2
49224	Calhoun County 68.7% Jackson County 31.3%	31.3%	2
49228	Lenawee County 99.5% Monroe County 0.5%	0.5%	2
49229	Lenawee County 87.9% Monroe County 10.8% Washtenaw County 1.3%	12.1%	3
49230	Jackson County 73.2% Lenawee County 26.8%	26.8%	2
49233	Jackson County 36.5% Hillsdale County 35.5% Lenawee County 28.0%	63.5%	3
49236	Lenawee County 54.8% Washtenaw County 45.2%	45.2%	2
49237	Jackson County 94.1% Calhoun County 5.9%	5.9%	2
49238	Lenawee County 70.1% Monroe County 29.9%	29.9%	2
49240	Jackson County 84.7% Washtenaw County 15.3%	15.3%	2
49245	Calhoun County 96.3% Branch County 2.1% Jackson County 1.6%	3.7%	3
49246	Jackson County 91.9% Hillsdale County 8.1%	8.1%	2
49247	Lenawee County 63.6% Hillsdale County 36.4%	36.4%	2
49249	Hillsdale County 96.2% Jackson County 3.9%	3.9%	2
49250	Hillsdale County 96.2% Jackson County 3.8%	3.8%	2
49251	Ingham County 94.9% Jackson County 5.1%	5.1%	2
49252	Hillsdale County 80.8% Branch County 7.7% Jackson County 6.7% Calhoun County 4.8%	19.3%	4
49255	Branch County 61.1% Hillsdale County 38.9%	38.9%	2
49264	Ingham County 71.7% Jackson County 26.4% Eaton County 1.9%	28.3%	3
49267	Monroe County 79.0% Lenawee County 21.0%	21.0%	2
49274	Hillsdale County 83.9% Branch County 16.1%	16.1%	2
49276	Lenawee County 68.9% Monroe County 31.1%	31.1%	2
49284	Jackson County 62.7% Calhoun County 30.0% Eaton County 7.3%	37.3%	3
49285	Ingham County 80.3% Jackson County 10.2% Livingston County 6.3% Washtenaw County 3.3%	19.8%	4
49287	Lenawee County 94.6% Washtenaw County 5.4%	5.4%	2
49288	Hillsdale County 87.4% Lenawee County 12.6%	12.6%	2
49302	Kent County 99.8% Ionia County 0.2%	0.2%	2
49303	Muskegon County 93.5% Newaygo County 6.5%	6.5%	2
49305	Mecosta County 83.9% Isabella County 16.1%	16.1%	2
49307	Mecosta County 80.3% Newaygo County 19.7%	19.7%	2
49309	Newaygo County 95.0% Lake County 5.0%	5.0%	2
49310	Isabella County 62.7% Mecosta County 35.0% Montcalm County 2.3%	37.3%	3
49315	Kent County 71.8% Ottawa County 18.1% Allegan County 10.1%	28.3%	3
49316	Kent County 79.1% Allegan County 18.3% Barry County 2.6%	20.9%	3
49318	Muskegon County 73.0% Ottawa County 23.1% Kent County 3.9%	27.0%	3
49323	Allegan County 99.0% Ottawa County 1.0%	1.0%	2
49325	Barry County 69.1% Ionia County 21.1% Kent County 9.7%	30.9%	3
49326	Kent County 60.0% Montcalm County 40.0%	40.0%	2
49327	Newaygo County 98.9% Muskegon County 0.6% Kent County 0.5%	1.1%	3
49329	Montcalm County 77.4% Newaygo County 22.6%	22.6%	2
49330	Kent County 87.4% Newaygo County 7.7% Ottawa County 3.8% Muskegon County 1.1%	12.6%	4
49331	Kent County 78.4% Ionia County 21.6%	21.6%	2
49333	Barry County 96.5% Kent County 2.3% Allegan County 1.3%	3.5%	3
49336	Mecosta County 90.2% Montcalm County 9.1% Newaygo County 0.8%	9.8%	3
49337	Newaygo County 94.3% Montcalm County 3.3% Mecosta County 2.4%	5.7%	3
49338	Newaygo County 70.3% Mecosta County 29.5% Osceola County 0.2%	29.7%	3
49339	Montcalm County 94.9% Newaygo County 5.1%	5.1%	2
49340	Mecosta County 70.7% Isabella County 29.3%	29.3%	2
49343	Kent County 52.6% Newaygo County 37.1% Montcalm County 10.3%	47.4%	3
49344	Allegan County 84.8% Barry County 15.2%	15.2%	2
49346	Mecosta County 96.8% Newaygo County 3.2%	3.2%	2
49347	Montcalm County 96.9% Kent County 3.1%	3.1%	2
49348	Allegan County 91.2% Barry County 6.8% Kent County 2.0%	8.8%	3
49402	Lake County 51.9% Mason County 47.1% Oceana County 1.0%	48.1%	3
49403	Ottawa County 88.9% Muskegon County 7.0% Kent County 4.1%	11.1%	3
49404	Ottawa County 93.5% Muskegon County 6.5%	6.5%	2
49411	Mason County 94.9% Manistee County 5.1%	5.1%	2
49412	Newaygo County 97.2% Oceana County 2.0% Muskegon County 0.8%	2.8%	3
49415	Muskegon County 91.7% Ottawa County 8.3%	8.3%	2
49418	Kent County 64.0% Ottawa County 36.0%	36.0%	2
49421	Oceana County 59.7% Newaygo County 40.3%	40.3%	2
49423	Allegan County 84.1% Ottawa County 15.9%	15.9%	2
49425	Muskegon County 62.9% Oceana County 27.6% Newaygo County 9.5%	37.1%	3
49426	Ottawa County 99.5% Allegan County 0.5%	0.5%	2
49434	Ottawa County 88.8% Allegan County 11.2%	11.2%	2
49435	Ottawa County 98.4% Kent County 1.6%	1.6%	2
49437	Muskegon County 61.3% Oceana County 38.7%	38.7%	2
49448	Ottawa County 80.3% Muskegon County 19.7%	19.7%	2
49449	Oceana County 69.8% Mason County 30.2%	30.2%	2
49451	Muskegon County 95.3% Ottawa County 3.9% Newaygo County 0.8%	4.7%	3
49456	Ottawa County 87.0% Muskegon County 13.0%	13.0%	2
49457	Muskegon County 97.1% Newaygo County 2.9%	2.9%	2
49459	Oceana County 94.6% Newaygo County 5.4%	5.4%	2
49464	Ottawa County 94.8% Allegan County 5.3%	5.3%	2
49534	Ottawa County 50.5% Kent County 49.5%	49.5%	2
49544	Kent County 96.1% Ottawa County 3.9%	3.9%	2
49601	Wexford County 88.1% Lake County 9.0% Missaukee County 2.9%	11.9%	3
49612	Antrim County 50.3% Kalkaska County 49.7%	49.7%	2
49613	Manistee County 58.9% Benzie County 41.1%	41.1%	2
49620	Grand Traverse County 52.6% Wexford County 47.4%	47.4%	2
49625	Manistee County 91.7% Wexford County 8.3%	8.3%	2
49630	Leelanau County 96.8% Benzie County 3.2%	3.2%	2
49631	Osceola County 85.1% Mecosta County 14.9%	14.9%	2
49633	Kalkaska County 72.6% Grand Traverse County 17.5% Wexford County 5.7% Missaukee County 4.1%	27.4%	4
49638	Wexford County 79.6% Manistee County 20.4%	20.4%	2
49639	Osceola County 77.3% Mecosta County 22.7%	22.7%	2
49640	Benzie County 96.7% Leelanau County 3.3%	3.3%	2
49643	Benzie County 61.4% Grand Traverse County 38.6%	38.6%	2
49644	Lake County 93.5% Mason County 3.7% Manistee County 2.8%	6.5%	3
49649	Grand Traverse County 91.0% Wexford County 9.0%	9.0%	2
49655	Osceola County 97.7% Lake County 2.3%	2.3%	2
49657	Missaukee County 99.7% Wexford County 0.3%	0.3%	2
49659	Antrim County 74.8% Kalkaska County 25.2%	25.2%	2
49660	Manistee County 81.8% Mason County 18.2%	18.2%	2
49663	Wexford County 66.8% Missaukee County 33.2%	33.2%	2
49665	Osceola County 64.6% Clare County 28.8% Missaukee County 6.6%	35.4%	3
49668	Wexford County 98.1% Manistee County 1.9%	1.9%	2
49676	Kalkaska County 70.9% Antrim County 29.1%	29.1%	2
49677	Osceola County 57.9% Lake County 30.3% Newaygo County 11.9%	42.1%	3
49679	Osceola County 86.7% Mecosta County 13.3%	13.3%	2
49683	Benzie County 70.7% Manistee County 22.6% Grand Traverse County 5.4% Wexford County 1.3%	29.3%	4
49684	Leelanau County 61.2% Grand Traverse County 32.6% Benzie County 6.2%	38.8%	3
49688	Osceola County 88.6% Lake County 10.5% Wexford County 0.9%	11.4%	3
49689	Manistee County 83.5% Wexford County 16.5%	16.5%	2
49690	Grand Traverse County 79.9% Kalkaska County 16.7% Antrim County 3.5%	20.1%	3
49701	Emmet County 62.1% Cheboygan County 37.9%	37.9%	2
49706	Emmet County 72.1% Cheboygan County 27.9%	27.9%	2
49707	Alpena County 97.8% Presque Isle County 2.3%	2.3%	2
49712	Charlevoix County 90.3% Antrim County 9.7%	9.7%	2
49713	Charlevoix County 94.4% Emmet County 3.7% Antrim County 2.0%	5.6%	3
49716	Emmet County 71.6% Cheboygan County 28.4%	28.4%	2
49718	Emmet County 81.1% Cheboygan County 18.9%	18.9%	2
49719	Mackinac County 82.1% Chippewa County 17.9%	17.9%	2
49720	Charlevoix County 91.3% Antrim County 8.7%	8.7%	2
49727	Antrim County 50.2% Charlevoix County 49.8%	49.8%	2
49729	Antrim County 84.3% Charlevoix County 15.7%	15.7%	2
49730	Antrim County 63.1% Otsego County 21.8% Charlevoix County 15.1%	36.9%	3
49733	Crawford County 87.7% Otsego County 12.3%	12.3%	2
49738	Crawford County 94.0% Kalkaska County 4.0% Otsego County 2.0%	6.0%	3
49746	Montmorency County 83.7% Alpena County 16.3%	16.3%	2
49747	Alcona County 55.0% Alpena County 45.0%	45.0%	2
49748	Chippewa County 91.7% Luce County 8.3%	8.3%	2
49751	Otsego County 70.0% Montmorency County 30.0%	30.0%	2
49755	Emmet County 76.4% Cheboygan County 23.6%	23.6%	2
49756	Oscoda County 61.9% Montmorency County 33.7% Crawford County 2.5% Otsego County 2.0%	38.1%	4
49760	Mackinac County 95.6% Chippewa County 4.4%	4.4%	2
49765	Presque Isle County 51.1% Cheboygan County 48.9%	48.9%	2
49769	Emmet County 88.2% Cheboygan County 11.8%	11.8%	2
49770	Emmet County 95.8% Charlevoix County 3.1% Cheboygan County 1.1%	4.2%	3
49774	Chippewa County 78.3% Mackinac County 21.7%	21.7%	2
49776	Presque Isle County 75.2% Alpena County 24.9%	24.9%	2
49780	Chippewa County 74.9% Mackinac County 25.1%	25.1%	2
49793	Chippewa County 79.0% Mackinac County 21.0%	21.0%	2
49795	Otsego County 84.5% Charlevoix County 7.9% Cheboygan County 7.5%	15.4%	3
49805	Keweenaw County 99.8% Houghton County 0.2%	0.2%	2
49807	Delta County 75.6% Menominee County 24.4%	24.4%	2
49817	Delta County 60.1% Schoolcraft County 39.9%	39.9%	2
49818	Marquette County 52.3% Delta County 47.7%	47.7%	2
49822	Alger County 98.1% Marquette County 1.9%	1.9%	2
49831	Dickinson County 67.6% Marquette County 32.4%	32.4%	2
49836	Schoolcraft County 79.8% Mackinac County 20.1%	20.1%	2
49853	Luce County 98.6% Mackinac County 1.4%	1.4%	2
49854	Schoolcraft County 94.4% Delta County 5.6%	5.6%	2
49861	Baraga County 90.5% Marquette County 9.5%	9.5%	2
49878	Delta County 97.2% Alger County 2.8%	2.8%	2
49879	Marquette County 63.5% Iron County 36.5%	36.5%	2
49880	Marquette County 57.1% Delta County 42.9%	42.9%	2
49883	Schoolcraft County 81.5% Alger County 18.5%	18.5%	2
49884	Alger County 56.2% Schoolcraft County 43.8%	43.8%	2
49885	Marquette County 84.5% Alger County 15.5%	15.5%	2
49892	Dickinson County 69.5% Menominee County 30.5%	30.5%	2
49895	Delta County 49.7% Alger County 44.3% Schoolcraft County 5.9%	50.3%	3
49913	Houghton County 92.7% Keweenaw County 7.3%	7.3%	2
49945	Houghton County 63.1% Keweenaw County 36.9%	36.9%	2
49947	Gogebic County 79.7% Ontonagon County 20.3%	20.3%	2
49948	Ontonagon County 98.4% Houghton County 1.6%	1.6%	2
49952	Houghton County 97.6% Ontonagon County 2.4%	2.4%	2
49958	Houghton County 69.9% Baraga County 30.1%	30.1%	2
49965	Houghton County 86.9% Ontonagon County 13.1%	13.1%	2
49967	Houghton County 44.1% Ontonagon County 36.6% Iron County 19.3%	55.9%	3
54540	Vilas County, WI 99.7% Gogebic County 0.3%	0.3%	2

What to do with this

If a ZIP code in your list is split, the ZIP alone cannot tell you which county an address is in. For most work that is fine. It matters when the county decides something: a sales tax rate, a licence, a franchise agreement written by county, or a service area somebody promised by county name.

The ZIP list audit checks your own list against the same Census data in your browser, and the ZIP spreadsheet comparison covers when a ZIP list is enough and when it is not.

What these numbers are, and are not

A ZCTA is not quite a ZIP code. ZIP Code Tabulation Areas are the Census Bureau's approximations of ZIP code areas, built by grouping census blocks by the ZIP codes of the addresses in them. USPS ZIP codes are delivery routes, not areas, and the two do not always match.
Some ZIP codes have no ZCTA at all. PO box ZIPs, ZIPs for a single building or a single large organisation, and military ZIPs usually have no area of their own, so they cannot be split across counties here and will not match any area in a map.
Land share is not population share. A ZCTA with 20% of its land in a second county might have almost none of its people there, or most of them. The shares here measure area, which is what the Census file publishes.
Tiny overlaps are included. A ZCTA counts as overlapping a county if the Census file lists any part of it there, including slivers along a road or river. That is why the share with at least 5% of land in a second county is shown alongside.

Source: U.S. Census Bureau, 2020 ZCTA to County relationship file, public domain. Counts use 2020 ZCTAs and 2020 county boundaries. ZIP codes added by USPS since then are not in it, and Connecticut's counties have since been replaced by planning regions in Census data.

Route by the boundary, not the ZIP

MapLogics decides who owns an address from a boundary you draw or import, so a ZIP that straddles two counties is answered by where the address actually is. There is a free trial if you want to see it on your own addresses.

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