Guidance for Using Tribal Boundaries, Areas and Names Resources

The EPA Office of Mission Support (OMS) provides six feature services depicting geographic information for federally recognized tribes. Their associated boundaries and locational information were developed by the U.S. Census Bureau (USCB) and the U.S. Bureau of Land Management, with other field attributes enhanced by OMS to meet Agency needs and use cases. These services may provide helpful information as EPA carries out activities relevant to Indian tribes, consistent with the EPA 1984 Indian Policy.

For national scale analyses and Agency-wide reporting, the six features below should be consulted as they relate to federally recognized tribes. Access a map service containing all seven datasets list below.

Developed in coordination with the American Indian Environmental Office (OITA-AIEO) and EPA Regions, this guidance details key information provided by USCB and BLM on the use of their tribal information. Please note: The services provided by OMS may be complemented by other tribal datasets as advised by the EPA Geospatial Advisory Committee (EGAC) and the Office of International and Tribal Affairs (OITA). Individual regions or program offices may supplement these services with other datasets as advised by their EGAC members and legal counsel on a case-specific basis.

Context for Tribal Boundaries & Areas

The U.S. Environmental Protection Agency (US EPA, EPA) administers federal environmental laws consistent with the requirements of such laws and applicable regulations, the federal trust responsibility to federally recognized tribes, the federal government-to-government relationships with such tribes, as well as the EPA Policy for the Administration of Environmental Programs on Indian Reservations—often referred to as the EPA 1984 Indian Policy. The EPA 1984 Indian Policy guides the Agency on how to consider tribal interests in protecting human health and the environment in Indian country and is complemented by the evolving legal and policy framework of the U.S. Federal Government.

On an annual basis, OMS updates and publishes a collection of feature services depicting geographic information for use in national-scale analyses and mapping applications. These data aid in the implementation of the EPA 1984 Indian Policy and other work EPA performs. The associated datasets contain information on six tribal categories: Alaska Native Allotments, Alaska Native Villages, American Indian Reservations, American Indian Off-reservation Trust Lands, Oklahoma Tribal Statistical Areas, and Virginia Federally Recognized Tribes. For each category, EPA has standardized and enhanced attributes provided by the U.S. Department of Commerce’s Bureau of the Census (USCB, or Census Bureau) and the U.S. Department of the Interior’s Bureau of Land Management (BLM) to best meet Agency needs and use cases. A map service including these tribal areas is located here.

None of the datasets provided by OMS are intended to constitute a determination of legal tribal or Indian country boundaries, nor of any entity’s jurisdictional authority or rights of ownership or entitlement. These data may only be used for general statistical collection and tabulation purposes. For instance, Oklahoma Tribal Statistical Areas are considered statistical entities, meaning that they are collected for statistical or tabulation purposes. Note that, consistent with the U.S. Supreme Court’s July 2020 decision in McGirt v. Oklahoma, the datasets describing Oklahoma Indian country boundaries are being refined. Any changes will be incorporated in future dataset iterations and clarified in this guidance, which will be updated as appropriate.

Alaska Native Allotments

Updated by BLM on November 9, 2019, Alaska Native Allotments were generated based on land survey records associated with the Public Land Survey System (PLSS) in Alaska (view here), specifically the BLM_AK_Native_Allotment_Convey feature service. According to BLM, the Alaska Native Allotment Act of 1906, the Alaska Native Claims Settlement Act (ANCSA), Section 905 of the Alaska National Interest Lands Conservation Act (ANILCA), the Alaska Native Vietnam Veterans Allotment Act of 1998, and the 2019 Alaska Native Vietnam era veterans land allotment section of the John D. Dingell, Jr., Conservation, Management, and Recreation Act (Public Law 116-9, Sec. 1119) informed the design and structure of these data.

Alaska Native Villages

Enacted in 1971, ANCSA was designed to settle aboriginal land title claims with Alaska Natives. Under the Act, specific regional or village corporations can select federal lands within their legally defined regions to be conveyed to them. EPA collected this Alaska Native Villages dataset from BLM during its last iteration on January 1, 2010 and updated it on July 28, 2021. These data are presented as boundary-centroid points based on selected and conveyed land boundaries provided by the BLM Alaska State Office.

American Indian Reservations

According to USCB, American Indian Reservations (AIRs) are areas set aside by the federal government for use by tribes. Their exterior boundaries are delineated in the final tribal treaties, agreements, executive orders, federal statutes, secretarial orders, and judicial determinations relevant to a given entity. The Bureau of Indian Affairs (BIA) maintains a list of all federally recognized tribal governments and makes final determination of the federal AIR inventory. The USCB recognizes these areas as territory over which American Indian tribes have primary governmental authority. AIRs can be legally described as colonies, communities, Indian colonies, Indian communities, Indian rancheria, Indian reservations, Indian villages, pueblos, rancherias, ranches, reservations, reserves, settlements, or villages. USCB contacts representatives of American Indian tribal governments to identify the boundaries for federal reservations through its annual Boundary and Annexation Survey. Federal reservations may cross state and all other area boundaries. These boundaries were updated on January 1, 2024, through the Boundary and Annexation Survey (BAS).

American Indian Off-reservation Trust Lands

The USCB defines Off-reservation Trust Lands (ORTLs) as areas for which the United States holds title in trust for the benefit of a tribe or for an individual American Indian. Trust lands may be located on or off an AIR, though USCB only tabulates data for ORTLs associated with a specific federally recognized reservation and/or tribal government. They may only be alienated or encumbered by the owner with the approval of the Secretary of the Interior or their authorized representative. As for federally recognized reservations, the Census Bureau obtains the boundaries of ORTLs from American Indian tribal governments through its annual BAS. The Census Bureau does not identify fee land (or land in fee simple status) or restricted fee lands as specific geographic areas. These boundaries were updated on January 1, 2024 through the BAS.

Oklahoma Statistical Areas

According to USCB, Oklahoma Tribal Statistical Area (OTSA) Joint-Use Areas, as applied to OTSAs by the Census Bureau, include areas administered jointly and/or claimed by two or more American Indian tribes that have a delineated OTSA. The Census Bureau designates statistical joint-use areas as unique geographic entities for the purpose of presenting statistical data. Only Oklahoma tribal statistical areas have statistical joint-use areas. These boundaries were updated on January 1, 2024, through the BAS.

Virginia Federally Recognized Tribes

Virginia Federally Recognized Tribes contains point data for federally recognized tribes geographically located in the state of Virginia, corresponding with the administrative boundaries of EPA Region 3. These tribes are federally recognized, but do not currently have land that qualifies as Indian country. Locations are based on mailing addresses for each tribe provided by the EPA Region 3 Tribal Program Coordinator to the US EPA Office of Mission Support on May 5, 2021.

Other Tribal Boundaries & Indigenous Areas

The EPA provides additional tribal boundary and area services that may complement the resources above given a specific use case. These data are provided through Shared Enterprise Geodata & Services and are standardized to meet Agency cartographic standards. These additional layers include: Alaska Native Regional Corporations, State-recognized American Indian Reservations, Hawaiian Native Home Lands, Tribal Cession Boundaries, and State-designated Tribal Statistical Areas. Terminology used within these services are referenceable online, including this summary document by USCB.

The following resources connect directly to APIs associated with EPA tribal boundaries and areas. These service URLs can be embedded into maps and related applications and should replace previous vintages of these data. Users can also download EPA stewarded services from the EPA Environmental Dataset Gateway from the EPA Metadata Record URLs at the top of this page:

Bureau of Indian Affairs (BIA) Tract Viewer: Mapped Lands in Indian Country

BIA’s Branch of Geospatial Support (BOGS) is the technical support office to Indian Affairs and all federally-recognized Tribes for geographic information systems (GIS) as a part of the Department of the Interior-Bureau of Indian Affairs Enterprise License Agreement (DOI-BIA ELA). BOGS assists Tribal governments and Indian Affairs to manage the cultural and natural resources of Indian country by providing geographic information systems software, training, and technical support.

BOGS maintains, hosts, and has made several geospatial resources publicly available. These resources can be found at Bureau of Indian Affairs (BIA) Open GIS Data These public datasets include the BIA Geospatial Tract Viewer (known as the BIA Tract Viewer) which displays all mapped Tribal, allotted, and jointly managed tracts and parcels for Tribal land area codes (LACs).

BIA uses nine datasets to generate the BIA Tract Viewer. These datasets include:

American Indian and Alaskan Native (AIAN) Mapped Land Area Representation (LAR) – The AIAN is a grouping of three distinct datasets: the AIAN National Land Areas Representation, the AIAN National LAR Supplemental, and the Tribal Statistical Areas.
Alaskan Native Villages are depicted as point locations and are not included in the BIA Tracts Viewer.
The tract and parcel data for the Alaskan Native Village townsites are not available in GIS format.
The absence of tracts and parcel data for the Alaskan Native Village townsites is not a reflection of ownership status.
American Indian / Alaska Native (AIAN) National Land Area Representation (LAR) – This LAR, last updated in 2019, displays Federally recognized Tribal reservations and trust land located off-reservation. It is the only layer within the BIA Tracts Viewer that includes reservation representation.
Land Areas may include reservation extents, trust lands, or a combination of both.
These units were created for the purpose of satisfying work identified in a Memorandum of Understanding (MOU) in effect from 2015 – 2019 with the U.S. Bureau of the Census. The spatial definition of each LAR feature appears as it was last published in 2019.
AIAN National LAR Supplemental –Includes nine additional Land Areas that follow the definitions for the AIAN LAR but have been maintained as a separate dataset distinct from the AIAN LAR.
The nine land areas are: Spirit Lake, Fallon, Fallon Colony, Eastern Cherokee, Navajo (Canoncito) Snoqualmie, Absentee Wyandotte of Colorado, Ponca Nebraska, and Paiute Indian Tribe of Utah.

Other BIA managed public datasets, including public data, tools, and resources available through can be found on the BIA Open GIS Data site, including information on federal projects, funding awards, and BIA offices. On this site, information is also available on:

BIA Agency, Regional, and Field Offices. The 12 regional offices and 78 agency offices located in the heart of Indian Country. The Bureau of Indian Affairs Central Office oversees all the regional offices and is also included in this dataset. Each agency is located within a defined regional boundary and works with the regional offices and reports to the BIA Deputy Director-Field Operations, located in Washington, D.C. These agencies are located at the reservation level and services the needs of specific tribes.

Federal Lands within Indian country. This is a webmap for the Excess Lands/ Restoring Homelands Application. The purpose of this dataset is to fulfill the public and Government’s need to know what agency is managing Federal land in a given area, and for use by Federal Staff for use in analysis and reports.

Alaska Native Regional Corporations

Updated in 2024, Alaska Native Regional Corporations (ANRC) are defined by the USCB pursuant to the Alaska Native Claims Settlement Act. ANRCs are corporate entities organized to conduct both for-profit and non-profit affairs of Alaska Natives pursuant to the Alaska Native Claims Settlement Act. They have legally defined boundaries that subdivide all of Alaska into twelve regions (except for the area within the Annette Island Reserve). The non-profit officials of ANRCs review their legal boundary and may, in the absence of participation by the Alaska Native village official, act as proxy in the delineation of Alaska Native Village Statistical Areas (ANVSAs) in their regions. Twelve ANRCs cover the entire State of Alaska except for the area within the Annette Island Reserve, which is recognized as an American Indian Reservation under the governmental authority of the Metlakatla Indian Community. There is a thirteenth ANRC that represents the eligible Alaska Natives living outside of Alaska that are not members of any of the twelve ANRCs within the State of Alaska. Because it has no defined geographic extent, this thirteenth ANRC does not appear in the TIGER/Line Shapefiles and the Census Bureau does not provide data for it. The Census Bureau offers representatives of the twelve ANRCs the opportunity to review and update the ANRC boundaries. ANRCs are represented by a 5-character FIPS code unique within Alaska and a nationally unique 8-character National Standard (GNIS) code.

State-recognized American Indian Reservations

State-recognized American Indian Reservations (AIRs) are reservations established by certain state governments for tribes recognized by the state. A governor-appointed state liaison provides the names and boundaries for state-recognized AIRs to the Census Bureau. State reservations must be defined within a single state but may cross county and other types of boundaries. To further identify and differentiate state-recognized AIRs from those that are federally recognized, the text, "(state)" is appended to the AIR name. Updated in 2024, these data align with the most current state reservations of state-recognized tribes.

Hawaiian Native Homelands

Updated by USCB in 2024, this dataset depicts the 75 Hawaiian homelands in the U.S. state of Hawaii. Hawaiian homelands are unique to Hawaii and are lands held in trust for Native Hawaiians by the state, pursuant to the Hawaiian Homes Commission Act of 1920 (HHCA), as amended. Passed by Congress and signed into law by President Warren Harding on July 9, 1921 (chapter 42, 42 Stat. 108), the HHCA provides for the rehabilitation of the native Hawaiian people through a government-sponsored homesteading program. Native Hawaiians are defined as individuals having at least 50 percent Hawaiian ancestry. Pursuant to provisions of the HHCA, the Department provides direct benefits to native Hawaiians in the form of 99-year homestead leases at an annual rental of $1. In 1990, the Legislature authorized the Department to extend leases for an aggregate term not to exceed 199 years (Act 305, Session Laws of Hawaii 1990; section 208, HHCA). Homestead leases are for residential, agricultural, or pastoral purposes. Aquacultural leases are also authorized, but none have been awarded to date. The intent of the homesteading program is to provide for economic self-sufficiency of native Hawaiians through the provision of land. Other benefits provided by the HHCA include financial assistance through direct loans or loan guarantees for home construction, replacement, or repair, and for the development of farms and ranches; technical assistance to farmers and ranchers; and the operation of water systems.

Tribal Cession Boundaries

USFS Tribal Cession Boundaries depict lands tribes have ceded to the federal government for which they may still retain rights and may not be present-day tribal boundaries. Tribal Cession Boundaries may be relevant to EPA in assessing where tribes continue to hold use or other rights through treaties, statutes, or executive orders. To create this feature service of cession maps, USFS scanned, georeferenced in JPEG2000 format, and digitized sixty-seven maps from “Indian Land Cessions in the United States.” These maps were compiled by Charles C. Royce and published as the second part of the two-part Eighteenth Annual Report of the Bureau of American Ethnology to the Secretary of the Smithsonian Institution, 1896-1897. The mapped cessions and reservations correspond to entries in the Schedule of Indian Land Cessions, which “indicates the number and location of each cession or reservation for the Indian tribes from the organization of the Federal Government to and including 1894, together with descriptions of the tracts so ceded or reserved, the date of the treaty, law or executive order governing the same, the name of the tribe or tribes affected thereby, and historical data and references bearing thereon."

State-designated Tribal Statistical Areas

Updated in 2024, State Designated Tribal Statistical Areas (SDTSAs) are delineated by the USCB. According to the Census Bureau, SDTSAs are statistical geographic areas identified and delineated for state recognized tribes that are not federally recognized and do not have an American Indian reservation or off-reservation trust land. The Census Bureau works with a governor appointed state liaison to delineate statistical areas for state-recognized tribes. SDTSAs do not cross state lines and are limited to the state in which the respective tribe is officially recognized. SDTSAs provide state recognized tribes without reservations statistical data for a geographic area that encompasses a substantial concentration of tribal members. SDTSAs were called State Designated American Indian Statistical Areas (SDAISAs) for Census 2000

Tribes Names Service

In addition to the geo based tribal information services described in this guidance document, EPA also provides web services that provide federally recognized tribe names sourced from BIA, corresponding BIA codes for federally recognized tribes, and EPA identifiers. These data are available for use in systems that are non-geospatial in nature. These services were developed to support implementation of EPAs Tribal Identification Data Standard. EPA requires applications that collect or manage tribal names to adopt these services. The TRIBES Services/Tribal Identifier Data Standard landing page provides access to a Tribe Entity Mapping spreadsheet that displays name changes over time, as well as the associated BIA codes and EPA internal identifiers. EPA strongly encourages use of EPA identifiers over BIA codes - BIA codes are not provided for Alaska Native Villages, and EPA has found some differences in Lower 48 BIA codes when comparing BIA code lists; BIA is aware of this issue and is working to address it. The Tribes Names Service does not provision State-recognized tribes. Please refer to this webpage for additional information.

Shared Enterprise Geodata & Services

The Office of Mission Support provides guidance on how to access tribal boundaries and areas in the EPA GeoPlatform. These data can be searched through Shared Enterprise Geodata and Services (SEGS) Data Discovery Tool and further examined using the EPA Clip and Ship Tool, which is linked to the Environmental Dataset Catalog. Please contact SEGServices@epa.gov with questions, comments, or feedback on these tribal boundary and area services. The National Geospatial Support Team (GeoServices@epa.gov) can answer questions related to GeoPlatform login and related applications.

EPA Region and Program Office Supplementary Data

Individual regions and program offices may wish to supplement these datasets with their own attributes or additional features. In some context, alternative datasets may provide boundaries at a finer resolution (spatial, temporal) than the data listed above. Among other things, such data may be useful for environmental screening and assessment. An example of this is the Tribal Nations Directory hosted by EPA Region 9. Please contact your GIS Lead or Regional Coordinator for additional information.

Data Use & Disclaimers

These data are protected under the Agency’s Terms of Use for Geospatial Data and were designed in accordance with the Federal Geospatial Data Committee’s Cadastral Content Data Standard. Corner positions were derived by geodetic calculations using measurement records. To the extent possible, coordinate-boundaries and/or locations were unmodified. However, in some cases, closure and edge-matching were necessary to produce a seamless dataset. Therefore, features may not preserve to original geometry of survey measurements even though record measurements are reported as attributes.

Please note that the EPA makes no claims regarding either the spatial accuracy or precision of these data and associated boundaries as coordinate locations were delineated by the U.S. federal agencies annotated in this metadata record. Data users are encouraged to carefully reference the metadata provided by these federal agencies before using this service. These data are not better than the sources from which they were derived, and both scale and accuracy may vary across the dataset. The inclusion of Indian country information in EPA systems does not represent any final EPA determination or action addressing Indian country locations or boundaries. This information cannot be relied upon to create any rights, substantive or procedural, enforceable by any party in litigation with the United States or third parties. EPA reserves the right to change this dataset at any time without public notice.