ZIP codes and county lines in Wisconsin

318 of the 783 ZIP code areas in Wisconsin, or 40.6%, 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: 783
In more than one county: 318
At least 5% in a second county: 234
Cross a state line: 1

How Wisconsin compares

Wisconsin ranks 14 of 52 (the 50 states, DC and Puerto Rico) by the share of its ZIP code areas that overlap more than one county. 72 of its counties have at least one split ZIP code area along an edge. 1 of its ZIP code areas also reach into Michigan, so a ZIP list that is meant to stop at the state line does not.

Counties with the most split ZIP code areas

Dane County: 19 ZIP codes shared with another county
Dunn County: 19 ZIP codes shared with another county
Marathon County: 19 ZIP codes shared with another county
Shawano County: 18 ZIP codes shared with another county
Clark County: 16 ZIP codes shared with another county

Every split ZIP code area in Wisconsin

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
53002	Washington County 97.9% Dodge County 2.1%	2.1%	2
53006	Dodge County 73.9% Fond du Lac County 26.1%	26.1%	2
53010	Fond du Lac County 94.9% Washington County 4.9% Dodge County 0.2%	5.1%	3
53011	Sheboygan County 98.7% Fond du Lac County 1.4%	1.4%	2
53012	Ozaukee County 68.5% Washington County 31.5%	31.5%	2
53013	Sheboygan County 81.2% Ozaukee County 18.8%	18.8%	2
53014	Calumet County 87.9% Manitowoc County 11.0% Fond du Lac County 1.1%	12.1%	3
53015	Manitowoc County 64.8% Sheboygan County 35.2%	35.2%	2
53017	Washington County 87.5% Waukesha County 12.5%	12.5%	2
53020	Sheboygan County 95.2% Manitowoc County 3.0% Calumet County 1.8%	4.8%	3
53021	Ozaukee County 81.0% Washington County 18.2% Sheboygan County 0.8%	19.0%	3
53027	Washington County 82.7% Dodge County 17.3%	17.3%	2
53029	Waukesha County 96.8% Washington County 3.2%	3.2%	2
53036	Jefferson County 70.5% Dodge County 24.7% Waukesha County 4.8%	29.4%	3
53040	Washington County 76.9% Sheboygan County 12.6% Fond du Lac County 10.5%	23.1%	3
53042	Manitowoc County 91.0% Calumet County 9.0%	9.0%	2
53048	Dodge County 96.5% Fond du Lac County 3.5%	3.5%	2
53049	Fond du Lac County 95.6% Calumet County 4.4%	4.4%	2
53061	Calumet County 82.0% Fond du Lac County 17.1% Manitowoc County 1.0%	18.0%	3
53065	Fond du Lac County 96.3% Dodge County 3.7%	3.7%	2
53066	Waukesha County 68.9% Jefferson County 17.0% Dodge County 13.8% Washington County 0.2%	31.1%	4
53075	Sheboygan County 86.7% Ozaukee County 10.1% Washington County 3.3%	13.3%	3
53079	Fond du Lac County 96.4% Sheboygan County 3.6%	3.6%	2
53090	Washington County 96.9% Ozaukee County 3.1%	3.1%	2
53091	Dodge County 96.4% Washington County 3.6%	3.6%	2
53095	Washington County 93.9% Ozaukee County 6.1%	6.1%	2
53098	Dodge County 100.0% Jefferson County under 0.1%	under 0.1%	2
53105	Racine County 40.9% Walworth County 37.5% Kenosha County 21.6%	59.1%	3
53114	Walworth County 75.5% Rock County 24.5%	24.5%	2
53118	Waukesha County 87.1% Jefferson County 12.9%	12.9%	2
53119	Waukesha County 88.8% Walworth County 9.0% Jefferson County 2.2%	11.2%	3
53120	Walworth County 91.3% Racine County 8.8%	8.8%	2
53126	Racine County 99.7% Milwaukee County 0.3%	0.3%	2
53128	Walworth County 85.9% Kenosha County 14.1%	14.1%	2
53139	Racine County 64.7% Kenosha County 35.3%	35.3%	2
53149	Waukesha County 84.4% Walworth County 8.6% Racine County 7.0%	15.6%	3
53150	Waukesha County 94.7% Racine County 5.3%	5.3%	2
53177	Racine County 87.0% Kenosha County 13.0%	13.0%	2
53182	Racine County 67.3% Kenosha County 32.7%	32.7%	2
53185	Racine County 99.2% Waukesha County 0.8%	0.8%	2
53190	Walworth County 49.0% Rock County 27.2% Jefferson County 23.8%	51.0%	3
53217	Milwaukee County 99.4% Ozaukee County 0.6%	0.6%	2
53225	Milwaukee County 98.5% Waukesha County 1.5%	1.5%	2
53227	Milwaukee County 99.6% Waukesha County 0.4%	0.4%	2
53403	Racine County 90.8% Kenosha County 9.2%	9.2%	2
53502	Green County 98.5% Rock County 1.5%	1.5%	2
53504	Lafayette County 55.3% Green County 44.7%	44.7%	2
53507	Iowa County 99.4% Dane County 0.6%	0.6%	2
53508	Dane County 65.8% Green County 34.2%	34.2%	2
53516	Lafayette County 47.7% Green County 35.5% Iowa County 13.7% Dane County 3.1%	52.3%	4
53517	Dane County 60.9% Iowa County 39.1%	39.1%	2
53518	Richland County 80.0% Grant County 15.9% Crawford County 4.2%	20.1%	3
53520	Rock County 53.3% Green County 46.7%	46.7%	2
53521	Green County 50.4% Dane County 41.1% Rock County 8.5%	49.6%	3
53522	Green County 94.9% Lafayette County 5.1%	5.1%	2
53523	Dane County 65.3% Jefferson County 34.7%	34.7%	2
53525	Rock County 94.6% Walworth County 5.4%	5.4%	2
53532	Dane County 85.1% Columbia County 14.9%	14.9%	2
53534	Rock County 51.6% Dane County 43.5% Jefferson County 4.9%	48.4%	3
53538	Jefferson County 98.3% Rock County 1.6%	1.6%	2
53543	Iowa County 82.1% Grant County 17.9%	17.9%	2
53544	Iowa County 99.1% Dane County 0.9%	0.9%	2
53554	Grant County 67.4% Iowa County 32.6%	32.6%	2
53555	Columbia County 78.4% Dane County 21.6%	21.6%	2
53556	Richland County 89.3% Sauk County 10.7%	10.7%	2
53559	Dane County 99.3% Jefferson County 0.7%	0.7%	2
53560	Dane County 91.8% Iowa County 8.3%	8.3%	2
53561	Sauk County 71.8% Columbia County 28.1%	28.1%	2
53563	Rock County 98.5% Jefferson County 1.6%	1.6%	2
53565	Iowa County 70.8% Lafayette County 29.2%	29.2%	2
53569	Grant County 53.9% Iowa County 46.1%	46.1%	2
53572	Dane County 99.3% Green County 0.7%	0.7%	2
53573	Grant County 42.1% Richland County 40.8% Iowa County 17.1%	57.9%	3
53574	Green County 97.4% Dane County 2.6%	2.6%	2
53578	Sauk County 80.9% Columbia County 19.1%	19.1%	2
53583	Sauk County 72.1% Dane County 27.7% Columbia County 0.1%	27.9%	3
53585	Walworth County 95.4% Rock County 4.6%	4.6%	2
53588	Sauk County 65.9% Iowa County 33.1% Richland County 1.0%	34.1%	3
53589	Dane County 97.9% Rock County 2.1%	2.1%	2
53594	Jefferson County 52.2% Dodge County 33.7% Dane County 14.2%	47.8%	3
53805	Grant County 64.1% Crawford County 35.9%	35.9%	2
53807	Grant County 59.1% Lafayette County 40.9%	40.9%	2
53811	Grant County 82.6% Lafayette County 17.4%	17.4%	2
53818	Grant County 81.1% Lafayette County 16.8% Iowa County 2.1%	18.9%	3
53821	Crawford County 77.4% Grant County 22.6%	22.6%	2
53901	Columbia County 98.7% Marquette County 1.3%	1.3%	2
53911	Columbia County 92.2% Dane County 7.8%	7.8%	2
53913	Sauk County 98.6% Columbia County 1.4%	1.4%	2
53920	Marquette County 55.9% Adams County 44.1%	44.1%	2
53923	Columbia County 89.9% Green Lake County 10.1%	10.1%	2
53924	Richland County 94.9% Sauk County 5.1%	5.1%	2
53925	Columbia County 53.9% Dodge County 36.0% Dane County 10.1%	46.1%	3
53926	Green Lake County 54.9% Marquette County 25.9% Columbia County 19.2%	45.1%	3
53929	Juneau County 72.2% Monroe County 16.8% Vernon County 11.0%	27.8%	3
53932	Columbia County 91.7% Dodge County 8.3%	8.3%	2
53937	Sauk County 72.1% Richland County 27.9%	27.9%	2
53941	Sauk County 93.9% Juneau County 5.8% Richland County 0.3%	6.1%	3
53944	Juneau County 83.0% Sauk County 17.0%	17.0%	2
53946	Green Lake County 93.2% Fond du Lac County 4.8% Marquette County 1.1% Dodge County 0.9%	6.8%	4
53949	Marquette County 96.0% Green Lake County 4.0%	4.0%	2
53952	Marquette County 50.3% Adams County 49.8%	49.8%	2
53954	Columbia County 90.6% Marquette County 9.4%	9.4%	2
53956	Columbia County 55.6% Dodge County 39.8% Green Lake County 4.7%	44.4%	3
53963	Fond du Lac County 54.3% Dodge County 45.8%	45.8%	2
53964	Marquette County 90.2% Adams County 8.4% Waushara County 1.4%	9.8%	3
53965	Adams County 55.9% Columbia County 21.1% Sauk County 16.8% Juneau County 6.3%	44.1%	4
53968	Juneau County 55.1% Sauk County 37.4% Vernon County 5.6% Richland County 1.9%	44.9%	4
54002	St. Croix County 96.9% Pierce County 3.1%	3.1%	2
54004	Barron County 67.2% Polk County 32.8%	32.8%	2
54005	Polk County 64.9% St. Croix County 19.7% Barron County 8.4% Dunn County 6.9%	35.1%	4
54007	St. Croix County 78.4% Polk County 21.6%	21.6%	2
54013	St. Croix County 96.5% Dunn County 3.5%	3.5%	2
54017	St. Croix County 96.8% Polk County 3.2%	3.2%	2
54020	Polk County 99.0% St. Croix County 1.0%	1.0%	2
54022	Pierce County 61.2% St. Croix County 38.8%	38.8%	2
54026	Polk County 75.7% St. Croix County 24.3%	24.3%	2
54103	Forest County 96.8% Marinette County 3.2%	3.2%	2
54104	Marinette County 99.2% Forest County 0.8%	0.8%	2
54106	Outagamie County 98.5% Shawano County 1.5%	1.5%	2
54107	Shawano County 97.3% Outagamie County 2.7%	2.7%	2
54110	Calumet County 73.0% Manitowoc County 24.2% Brown County 2.8%	27.0%	3
54111	Shawano County 92.4% Oconto County 7.6%	7.6%	2
54112	Marinette County 71.7% Oconto County 28.3%	28.3%	2
54114	Marinette County 91.8% Oconto County 8.2%	8.2%	2
54115	Brown County 84.9% Outagamie County 15.1%	15.1%	2
54120	Florence County 85.7% Marinette County 14.3%	14.3%	2
54124	Oconto County 92.5% Menominee County 7.4% Shawano County 0.2%	7.5%	3
54125	Marinette County 70.4% Forest County 29.6%	29.6%	2
54126	Brown County 99.4% Manitowoc County 0.6%	0.6%	2
54130	Outagamie County 78.8% Calumet County 10.9% Brown County 10.4%	21.2%	3
54137	Shawano County 59.0% Oconto County 41.0%	41.0%	2
54139	Oconto County 98.5% Marinette County 1.6%	1.6%	2
54150	Menominee County 97.0% Shawano County 3.0%	3.0%	2
54151	Marinette County 71.4% Florence County 28.6%	28.6%	2
54154	Oconto County 89.5% Shawano County 10.5%	10.5%	2
54155	Brown County 50.1% Outagamie County 49.9%	49.9%	2
54157	Marinette County 98.0% Oconto County 2.0%	2.0%	2
54161	Oconto County 51.5% Marinette County 48.5%	48.5%	2
54162	Shawano County 61.2% Brown County 22.5% Oconto County 16.3%	38.8%	3
54165	Outagamie County 87.8% Shawano County 11.1% Brown County 1.1%	12.2%	3
54170	Outagamie County 74.5% Shawano County 22.3% Waupaca County 3.2%	25.5%	3
54174	Oconto County 63.9% Menominee County 36.1%	36.1%	2
54175	Oconto County 99.3% Langlade County 0.7%	0.7%	2
54180	Brown County 85.0% Outagamie County 15.0%	15.0%	2
54201	Kewaunee County 91.7% Door County 8.3%	8.3%	2
54205	Kewaunee County 97.8% Door County 2.2%	2.2%	2
54208	Brown County 59.0% Kewaunee County 29.2% Manitowoc County 11.8%	41.0%	3
54213	Door County 89.9% Kewaunee County 10.1%	10.1%	2
54217	Kewaunee County 80.3% Brown County 11.8% Door County 7.9%	19.7%	3
54313	Brown County 98.8% Outagamie County 1.3%	1.3%	2
54405	Marathon County 75.3% Clark County 24.7%	24.7%	2
54408	Marathon County 86.8% Shawano County 9.0% Langlade County 4.2%	13.2%	3
54409	Langlade County 87.7% Marathon County 8.5% Shawano County 3.8%	12.3%	3
54411	Marathon County 94.3% Taylor County 5.7%	5.7%	2
54412	Wood County 64.8% Marathon County 35.2%	35.2%	2
54414	Shawano County 61.1% Marathon County 38.5% Langlade County 0.4%	38.9%	3
54420	Clark County 91.2% Wood County 8.8%	8.8%	2
54421	Marathon County 55.1% Clark County 44.9%	44.9%	2
54422	Clark County 77.0% Taylor County 22.9%	22.9%	2
54425	Clark County 57.5% Marathon County 31.3% Taylor County 11.2%	42.5%	3
54427	Marathon County 76.0% Shawano County 24.0%	24.0%	2
54428	Langlade County 96.0% Oneida County 4.0%	4.0%	2
54433	Taylor County 88.7% Chippewa County 11.3%	11.3%	2
54435	Lincoln County 58.2% Langlade County 41.8%	41.8%	2
54443	Portage County 99.1% Wood County 0.8% Marathon County 0.1%	0.9%	3
54449	Wood County 71.4% Marathon County 28.4% Clark County 0.2%	28.6%	3
54451	Taylor County 98.3% Marathon County 1.7%	1.7%	2
54452	Lincoln County 89.4% Marathon County 10.6%	10.6%	2
54454	Wood County 94.9% Portage County 5.1%	5.1%	2
54455	Marathon County 92.7% Portage County 7.3%	7.3%	2
54457	Adams County 42.1% Wood County 34.6% Juneau County 23.3%	57.9%	3
54459	Price County 98.6% Lincoln County 1.4%	1.4%	2
54460	Clark County 81.7% Taylor County 18.4%	18.4%	2
54463	Oneida County 98.0% Langlade County 2.0%	2.0%	2
54465	Forest County 62.3% Langlade County 37.7%	37.7%	2
54466	Wood County 53.5% Jackson County 42.1% Clark County 4.4%	46.5%	3
54470	Taylor County 97.6% Price County 2.4%	2.4%	2
54473	Portage County 76.3% Marathon County 23.7%	23.7%	2
54475	Wood County 82.2% Portage County 17.8%	17.8%	2
54479	Clark County 56.2% Marathon County 43.8%	43.8%	2
54480	Taylor County 92.2% Marathon County 7.8%	7.8%	2
54486	Shawano County 81.3% Waupaca County 18.7%	18.7%	2
54487	Lincoln County 73.8% Oneida County 26.3%	26.3%	2
54488	Clark County 53.6% Marathon County 46.4%	46.4%	2
54490	Taylor County 99.5% Price County 0.5%	0.5%	2
54491	Langlade County 91.1% Oconto County 8.9%	8.9%	2
54494	Wood County 56.8% Portage County 40.0% Adams County 3.2%	43.2%	3
54498	Clark County 50.6% Taylor County 49.4%	49.4%	2
54499	Shawano County 68.8% Marathon County 29.7% Portage County 1.5%	31.2%	3
54501	Oneida County 98.0% Lincoln County 2.0%	2.0%	2
54514	Ashland County 81.0% Price County 12.7% Iron County 6.3%	18.9%	3
54517	Ashland County 56.6% Sawyer County 31.2% Bayfield County 12.2%	43.4%	3
54521	Vilas County 64.2% Oneida County 30.3% Forest County 5.5%	35.8%	3
54530	Rusk County 71.2% Price County 24.3% Sawyer County 4.5%	28.8%	3
54538	Vilas County 76.6% Iron County 12.4% Oneida County 10.2% Price County 0.9%	23.4%	4
54540	Vilas County 99.7% Gogebic County, MI 0.3%	0.3%	2
54542	Forest County 61.1% Florence County 38.9%	38.9%	2
54545	Vilas County 99.9% Iron County 0.1%	0.1%	2
54548	Oneida County 82.0% Vilas County 18.0%	18.0%	2
54552	Price County 71.5% Iron County 25.5% Sawyer County 3.0%	28.5%	3
54557	Vilas County 98.8% Iron County 1.2%	1.2%	2
54558	Vilas County 75.7% Oneida County 24.3%	24.3%	2
54559	Iron County 85.3% Ashland County 14.7%	14.7%	2
54562	Oneida County 62.8% Forest County 37.2%	37.2%	2
54564	Oneida County 64.7% Lincoln County 33.9% Price County 1.4%	35.3%	3
54566	Forest County 92.1% Langlade County 7.9%	7.9%	2
54568	Vilas County 86.1% Oneida County 13.9%	13.9%	2
54612	Trempealeau County 72.3% Buffalo County 27.6%	27.6%	2
54615	Jackson County 97.3% Monroe County 2.7%	2.7%	2
54616	Trempealeau County 87.2% Jackson County 12.8%	12.8%	2
54618	Juneau County 70.3% Monroe County 29.7%	29.7%	2
54619	Monroe County 73.8% Vernon County 22.4% La Crosse County 3.8%	26.2%	3
54623	La Crosse County 57.4% Vernon County 42.6%	42.6%	2
54624	Vernon County 85.5% Crawford County 14.5%	14.5%	2
54627	Trempealeau County 88.1% Jackson County 11.9%	11.9%	2
54628	Crawford County 91.5% Vernon County 8.5%	8.5%	2
54634	Vernon County 69.4% Richland County 30.0% Juneau County 0.6%	30.6%	3
54638	Monroe County 84.0% Vernon County 13.3% Juneau County 2.8%	16.0%	3
54639	Vernon County 95.9% Richland County 4.1%	4.1%	2
54642	Jackson County 92.8% Trempealeau County 4.3% La Crosse County 2.9%	7.2%	3
54644	La Crosse County 94.0% Jackson County 6.0%	6.0%	2
54651	Vernon County 57.0% Monroe County 43.0%	43.0%	2
54653	La Crosse County 61.0% Monroe County 39.0%	39.0%	2
54655	Crawford County 82.2% Richland County 15.6% Vernon County 2.3%	17.8%	3
54656	Monroe County 99.9% La Crosse County 0.1%	0.1%	2
54658	Vernon County 92.0% La Crosse County 8.0%	8.0%	2
54659	Jackson County 97.5% Trempealeau County 2.5%	2.5%	2
54661	Trempealeau County 99.7% La Crosse County 0.3%	0.3%	2
54664	Richland County 65.3% Vernon County 34.8%	34.8%	2
54665	Vernon County 99.0% Crawford County 1.0%	1.0%	2
54666	Monroe County 45.4% Jackson County 43.9% Juneau County 10.7%	54.6%	3
54667	Vernon County 96.6% La Crosse County 3.4%	3.4%	2
54701	Eau Claire County 95.3% Dunn County 4.7%	4.7%	2
54703	Eau Claire County 77.6% Chippewa County 20.7% Dunn County 1.7%	22.4%	3
54721	Pepin County 85.7% Dunn County 12.1% Pierce County 2.3%	14.3%	3
54724	Chippewa County 99.4% Dunn County 0.6%	0.6%	2
54726	Chippewa County 71.9% Eau Claire County 28.1%	28.1%	2
54727	Chippewa County 94.5% Eau Claire County 5.5%	5.5%	2
54728	Barron County 80.2% Rusk County 19.0% Dunn County 0.8%	19.8%	3
54729	Chippewa County 96.9% Eau Claire County 3.1%	3.1%	2
54730	Dunn County 77.8% Chippewa County 22.2%	22.2%	2
54734	Dunn County 94.0% St. Croix County 6.0%	6.0%	2
54736	Pepin County 50.3% Buffalo County 44.9% Dunn County 4.8%	49.7%	3
54737	Dunn County 94.6% Pepin County 5.4%	5.4%	2
54738	Eau Claire County 53.5% Trempealeau County 45.5% Buffalo County 1.0%	46.5%	3
54739	Dunn County 81.7% Chippewa County 18.2% Eau Claire County 0.1%	18.3%	3
54740	Pierce County 57.7% Dunn County 42.3%	42.3%	2
54741	Eau Claire County 48.0% Jackson County 39.3% Clark County 12.8%	52.0%	3
54745	Chippewa County 85.2% Rusk County 14.8%	14.8%	2
54746	Clark County 82.6% Jackson County 17.4%	17.4%	2
54747	Trempealeau County 63.2% Buffalo County 36.8%	36.8%	2
54749	Dunn County 83.9% St. Croix County 16.1%	16.1%	2
54754	Jackson County 82.7% Clark County 17.3%	17.3%	2
54755	Buffalo County 60.1% Dunn County 14.3% Pepin County 13.5% Eau Claire County 12.1%	39.9%	4
54757	Chippewa County 56.0% Barron County 19.7% Dunn County 16.2% Rusk County 8.1%	44.0%	4
54758	Trempealeau County 52.8% Jackson County 24.5% Eau Claire County 22.6%	47.2%	3
54762	Barron County 86.9% Dunn County 13.1%	13.1%	2
54763	Dunn County 83.5% Barron County 16.6%	16.6%	2
54766	Taylor County 51.6% Rusk County 38.1% Chippewa County 10.3%	48.4%	3
54767	Pierce County 82.4% St. Croix County 12.1% Dunn County 5.4%	17.6%	3
54768	Chippewa County 45.0% Clark County 32.6% Taylor County 12.9% Eau Claire County 9.6%	55.0%	4
54769	Pepin County 73.8% Pierce County 26.2%	26.2%	2
54770	Trempealeau County 73.5% Eau Claire County 26.5%	26.5%	2
54771	Clark County 88.3% Taylor County 11.8%	11.8%	2
54801	Washburn County 79.2% Burnett County 20.8%	20.8%	2
54806	Ashland County 66.7% Bayfield County 33.3%	33.3%	2
54813	Burnett County 52.5% Barron County 31.9% Washburn County 15.6%	47.5%	3
54817	Washburn County 33.9% Sawyer County 32.3% Rusk County 19.7% Barron County 14.1%	66.1%	4
54820	Douglas County 52.2% Bayfield County 47.8%	47.8%	2
54821	Bayfield County 97.9% Sawyer County 2.1%	2.1%	2
54826	Polk County 55.2% Barron County 44.8%	44.8%	2
54829	Barron County 74.9% Polk County 25.1%	25.1%	2
54830	Burnett County 62.3% Douglas County 37.6% Washburn County 0.1%	37.7%	3
54835	Sawyer County 82.2% Rusk County 17.9%	17.9%	2
54837	Polk County 82.4% Burnett County 17.6%	17.6%	2
54838	Douglas County 98.3% Bayfield County 1.8%	1.8%	2
54840	Burnett County 88.1% Polk County 11.9%	11.9%	2
54843	Sawyer County 92.1% Washburn County 7.9%	7.9%	2
54853	Polk County 96.1% Burnett County 3.9%	3.9%	2
54856	Bayfield County 98.5% Ashland County 1.5%	1.5%	2
54859	Washburn County 81.0% Douglas County 15.8% Burnett County 3.3%	19.1%	3
54868	Barron County 94.3% Rusk County 4.5% Washburn County 1.1%	5.7%	3
54870	Washburn County 97.1% Barron County 2.9%	2.9%	2
54871	Washburn County 57.6% Burnett County 42.4%	42.4%	2
54872	Burnett County 94.4% Polk County 5.6%	5.6%	2
54873	Douglas County 63.9% Bayfield County 36.1%	36.1%	2
54876	Sawyer County 58.3% Washburn County 41.8%	41.8%	2
54889	Polk County 55.2% Barron County 44.8%	44.8%	2
54904	Winnebago County 99.5% Fond du Lac County 0.5%	0.5%	2
54909	Portage County 82.4% Waushara County 17.6%	17.6%	2
54914	Outagamie County 96.2% Winnebago County 3.8%	3.8%	2
54915	Calumet County 50.0% Outagamie County 44.2% Winnebago County 5.8%	50.0%	3
54921	Portage County 86.3% Adams County 13.7%	13.7%	2
54922	Outagamie County 54.6% Waupaca County 45.4%	45.4%	2
54923	Waushara County 48.4% Green Lake County 43.2% Winnebago County 8.4%	51.6%	3
54929	Waupaca County 72.7% Shawano County 25.4% Outagamie County 2.0%	27.3%	3
54930	Waushara County 56.1% Adams County 41.0% Marquette County 2.9%	43.9%	3
54940	Waushara County 30.6% Waupaca County 29.8% Winnebago County 29.7% Outagamie County 9.9%	69.4%	4
54943	Waushara County 53.2% Adams County 46.8%	46.8%	2
54945	Waupaca County 98.5% Portage County 1.5%	1.5%	2
54950	Waupaca County 67.6% Shawano County 32.4%	32.4%	2
54952	Calumet County 77.2% Winnebago County 22.8%	22.8%	2
54956	Winnebago County 96.5% Outagamie County 3.5%	3.5%	2
54960	Marquette County 62.2% Waushara County 19.2% Green Lake County 18.5%	37.8%	3
54961	Waupaca County 64.2% Outagamie County 35.8%	35.8%	2
54963	Winnebago County 99.6% Waushara County 0.4%	0.4%	2
54964	Winnebago County 71.8% Fond du Lac County 28.2%	28.2%	2
54965	Waushara County 98.7% Waupaca County 1.3%	1.3%	2
54966	Waushara County 73.7% Portage County 18.9% Adams County 7.5%	26.4%	3
54968	Green Lake County 81.4% Marquette County 18.6%	18.6%	2
54971	Fond du Lac County 59.5% Green Lake County 20.7% Winnebago County 19.9%	40.5%	3
54977	Waupaca County 88.0% Portage County 12.0%	12.0%	2
54979	Fond du Lac County 95.7% Winnebago County 4.3%	4.3%	2
54981	Waupaca County 91.5% Portage County 5.0% Waushara County 3.5%	8.6%	3
54982	Waushara County 97.8% Marquette County 2.2%	2.2%	2
54983	Waupaca County 92.7% Waushara County 7.3%	7.3%	2
54984	Waushara County 97.2% Portage County 2.8%	2.8%	2
54986	Winnebago County 99.1% Waushara County 0.9%	0.9%	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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