United States/Boundaries

Boundaries of states, counties, and county equivalents in the continental United States ("lower 48" states) plus Alaska and Hawaii

The borders of the United States and those of its political subdivisions are represented by administrative boundary relations. The boundary=administrative, border_type=*, and admin_level=* tags are applied to these relations (and often their member ways, for software compatibility reasons) to indicate their relative importance.

Renderers typically display these boundaries as dotted lines and may use boundary relations for other purposes, such as to display state-appropriate highway shields. Geocoders use the boundary relations to identify places and construct full addresses. For debugging purposes, ito! Map has a map of administrative boundaries in the United States, color-coded by admin_level=* tags on ways (not relations, unfortunately).

This article is a basic tagging guide. It discusses tagging practices that either are already in wide use in OSM or have achieved consensus through the proposal process. In the interest of clarity, this article does not discuss novel tagging proposals. There are numerous exceptions to the information below, some of them quite significant, but this article ignores them in order to focus on how to tag new features as they come up. For a more detailed explanation of the various governmental structures described in this article, see United States admin level and the Wikipedia series on Political divisions of the United States.

Summary

The following table contains generalizations meant to reflect current usage in OSM.

If you don't see an entry corresponding to the kind of boundary you're trying to map, consult the corresponding section for more details. If the section doesn't say how to tag the boundary either, it could be that similar boundaries have yet to be mapped, or perhaps the community has yet to reach consensus on how to tag them. In that case, try to be consistent with the entries below when mapping, and let the talk-us mailing list know what you come up with.

admin_level=* values (border_type=* values in parentheses)

4	5	6	7	8	9	10
State or Territory (state)	N/A	County (county)	Civil township (township)	Municipality (city, village)	N/A	Neighborhood (neighbourhood, district)
Alaska	N/A	Borough	N/A	City	N/A	N/A
California	N/A	County	N/A	City Town	N/A	Neighborhoods
Connecticut	N/A	County	Town	City Borough	N/A	N/A
Florida	N/A	County	N/A	City Town Village	N/A	N/A
Hawaii	N/A	County	N/A	N/A	N/A	N/A
Illinois	N/A	County	N/A	City Village Town	N/A	N/A
Louisiana	N/A	Parish	N/A	City Town Village	N/A	N/A
Maine	N/A	County	Town	City	N/A	N/A
Massachusetts	N/A	County	N/A	City Town	N/A	N/A
Michigan	N/A	County	N/A	City	N/A	N/A
	N/A	County	Township Charter township	Village	N/A	N/A
Minnesota	N/A	County	N/A	City	N/A	Neighborhood
New Hampshire	N/A	County	N/A	City Town	N/A	N/A
New Jersey	N/A	County	N/A	Borough City Town Township Village	N/A	N/A
New York	New York City	Borough	N/A	N/A	N/A	N/A
	N/A	County	N/A	City Hamlet	N/A	N/A
	N/A	County	Town	Village	N/A	N/A
Ohio	N/A	County	Township	City Village	N/A	Neighborhood
Pennsylvania	N/A	County	N/A	City	N/A	N/A
	N/A	County	N/A	Township Borough Village Hamlet	N/A	N/A
Rhode Island	N/A	County	N/A	City	N/A	N/A
Vermont	N/A	County	Town	City	N/A	N/A
Virginia	N/A	Independent city	N/A	N/A	N/A	N/A
	N/A	County	N/A	Town	N/A	N/A
Wisconsin	N/A	County	Town	City Village	N/A	N/A
District of Columbia	N/A	N/A	N/A	City	N/A	Neighborhood
American Samoa	N/A	County	N/A	Village	N/A	N/A
Guam	N/A	N/A	N/A	Village	N/A	N/A
Northern Mariana Islands	N/A	Municipality	N/A	N/A	N/A	N/A
Puerto Rico	N/A	Municipality (municipio)	N/A	Ward (barrio)	N/A	N/A
United States Virgin Islands	N/A	District	N/A	Subdistrict	N/A	N/A

National boundary

The United States–Mexico border at San Diego, California, and Tijuana, Baja California

The federal border is represented by 148838 148838, tagged boundary=administrative border_type=national admin_level=2. Where this border delineates U.S. territorial waters (e.g., 12 nautical miles off the Atlantic coast), the member way is tagged border_type=territorial maritime=yes. State and territorial boundary relations are members of this national boundary relation with the role subarea.

States in Free Association

The freely associated states (Marshall Islands, Federated States of Micronesia, and Palau) have national-level admin_level=2 boundaries of their own and are excluded from the United States' national boundary relation. This is because they are sovereign nations under a Compact of Free Association.

States, Territories, and the District of Columbia

Main article: United States State Boundary Relations

An Arizona welcome sign at the border with New Mexico

The borders of states, the District of Columbia, and Territories, including Commonwealths, are tagged boundary=administrative border_type=state admin_level=4. As of July 2017, none of the Territory known as the United States Minor Outlying Islands has a boundary relation.

Where the border delineates state territorial waters (e.g., 3 nautical miles off the Atlantic coast), the member way is tagged border_type=state maritime=yes. Generally, borders along waterways follow the deepest path along the channel (known as a thalweg). However, state river borders are more nuanced, especially along the Mississippi River and Ohio River, whose banks have changed significantly over the centuries. Do not expect to be able to "eyeball" a border along a river using aerial imagery.

Counties, parishes, boroughs, etc.

A sign marking the border between Summit and Medina counties in Ohio

Boundary relations of counties (including parishes in Louisiana and boroughs in Alaska) are tagged boundary=administrative border_type=county admin_level=6. The counties of Connecticut [1] and Rhode Island [2] are also tagged this way, even though these states have no governments at the county level.

A county boundary relation's name=* tag should include the word "County".

County boundaries were imported from USGS data, which is accurate but has lower resolution than other types of data in OSM.

Regardless of their names, the counties of American Samoa, municipalities of Puerto Rico and Northern Mariana Islands, and districts of the U.S. Virgin Islands are all tagged admin_level=6, just like the counties of states. As of July 2017, the districts of American Samoa have not been mapped.

More information about county boundaries by state:

• Georgia
• Ohio
• Wyoming

Civil townships

Welcome sign at the border of Meridian Charter Township, Ingham County, Michigan. Note that townships and municipalities sometimes place welcome signs at the entrance to business districts rather than their borders.

Civil townships exist as administrative units in 20 states. They are usually known as townships or towns and are characterized by the fact that they subdivide counties completely. Depending on the state, it may be possible for a city or village to be subordinate to one or more townships, or for a city or village to withdraw from a township, becoming a direct subdivision of the county. These nuances inform the following table indicating common tagging practices by state:

Civil township tagging by state

State	border_type	admin_level
Connecticut	town	7
Indiana	township	7
Kansas	township	7
Maine	town	7
Michigan	township	7
New Hampshire	town	8
New Jersey	township	8
New York	town	7
Ohio	township	7
Pennsylvania	township	8
Vermont	town	7
Wisconsin	town	7

The TIGER 2005 import omitted the boundaries of minor civil divisions, including civil townships. Mappers have been adding them in by hand, often tracing their boundaries from the USGS Topographic Maps layer. Township boundaries are generally shown as black dashed lines. The topo layer can also be slightly misaligned in places. It helps to switch back to aerial photography once in awhile, as a sanity check. If you know the general vicinity of a township line, you may also be able to spot a change in pavement quality where one township has repaved their road up to the township line.

Municipalities

Main article: United States municipalities

A sign marking the border at Schulenburg's city limit, Texas

Municipalities are known by many names, such as city, town, township, village, and hamlet. Especially as it is known in the fifty states as "incorporated," tag a municipality with admin_level=8 and the appropriate border_type=* tag, such as border_type=city. In rare cases, an unincorporated community may have well-defined borders that justify a boundary relation.

Again, note that "municipality" in non-fifty-state areas of the US (territories and the like) means something specific and different from a "city-like municipality" as just described. These "municipalities" (not in states) are always admin_level=6. They can go by different names in any given Territory (District, Village, Unorganized Atoll, Island, Island Group, Municipio) but denoting a "municipality" in these regions effectively means "county equivalent" (admin_level=6).

A consolidated city-county (CCC) is mapped as two separate, coextensive boundaries, one for the city (admin_level=8) and the other for the county (admin_level=6). On the other hand, an independent city – that is, a city independent of any county – is mapped as a single border_type=city admin_level=6 boundary.

Municipal boundaries were imported from TIGER 2005 shapefile data, which is often very high resolution but contains countless inaccuracies. The USGS Topographic Maps layer may be a useful resource for realigning municipal boundaries. However, unlike civil townships, municipal boundaries are far more likely to change over time due to annexation, so the USGS maps may be outdated with respect to city limits.

Municipal subdivisions

Medium and large cities may have formal subdivisions, variously called neighborhoods, districts, boroughs, or wards. Where these subdivisions serve as a system of general-purpose units of government with well-defined boundaries, they are tagged admin_level=10 and the appropriate border_type=* tag. In some cities, these subdivisions may correspond to voting districts, but this is not necessarily the case with every city. In cities which contain both wards and neighborhoods (as does New Orleans), it may make sense to tag the wards admin_level=9 and the neighborhoods admin_level=10, to preserve this hierarchy. New Orleans might chime in and suggest that wards are administrative and neighborhoods are not; there is little or no consensus here.

For example, each neighborhood of Cincinnati, Ohio, has a semiformal neighborhood council, and the neighborhood boundaries are well-known. By contrast, many of the neighborhoods of San Jose, California, are amorphous, so they are instead mapped as place=suburb nodes. Naturally, there is a lot of gray area between these extremes, so use common sense. If the boundaries of a neighborhood are subjective and impossible to verify using signage alone, chances are that the neighborhood should be mapped as a node.

Examples of cities with formal subdivisions:

• Chicago, Illinois
• Cincinnati, Ohio
• Cleveland, Ohio
• Minneapolis, Minnesota
• Seattle, Washington
• Washington, D.C.

In smaller cities, especially suburbs, consider mapping homeowner association–managed residential subdivisions with landuse=residential ways. However, some planned communities such as The Woodlands, Texas, have a formal system of named subdivisions, which are mapped with boundary relations.

Notable exceptions

• The New York City boundary relation is tagged admin_level=5. It encompasses several county-level boroughs (an example of "county equivalent"), which are tagged admin_level=6.
• The Reedy Creek Improvement District in Florida, near Walt Disney World, is tagged admin_level=7.
• The boundary relation for Washington, D.C., is 5396194 5396194. Like most other municipal boundary relations, it is tagged admin_level=8. Currently (July, 2017) there is no admin_level=6 relation within the District of Columbia, although the Census Bureau does consider the city of Washington, DC a "county equivalent" (similar to a Consolidated City County, but strictly speaking, not a CCC).

Other types of boundaries

• For Indian reservations, see WikiProject US American Indian Reservations.
• Census-designated places (CDPs) are statistical areas, not administrative areas. The TIGER fixup project is deleting outdated CDPs and retagging relevant ones from boundary=administrative admin_level=8 to boundary=census (without an admin_level=* tag).
• ZIP codes are not boundaries at all.

Other uses of admin_level

The admin_level=* values described above also apply to the following tags:

• capital=* – A state capital is tagged capital=4, and a county seat is tagged capital=6.
• heritage=* – For example, a National Historic Landmark is tagged heritage=2, signifying that its historical status is registered with the national-level National Register of Historic Places.