Wild, Wild Research in the Western States

By Dayna Jacobs, AG®

Sponsored by International Commission for the Accreditation of Professional Genealogists (ICAPGenSM)


Research in the Western States requires thinking on a large scale; the area stretches from Canada to Mexico, was part of seven countries’ histories (Spain, Mexico, France, Great Britain, Russia, Republic of Texas, and the United States) and had a large indigenous population with its own history.  The climate and geography vary on the broadest scale, from snowy mountaintops and plains to hot, arid, deserts and valleys.

Modern-day boundaries for the lower 48 states and territories were finalized in 1868.  California was the first Western state admitted to the Union (1850) while Arizona and New Mexico were the last (1912).  Alaska and Hawaii followed in 1959.

The western United States was first inhabited by indigenous peoples.  The first foreigners to arrive and establish permanent settlements were Spaniards who established a trade route from Mexico City to San Juan Pueblo (near Santa Fe, New Mexico) in 1598.  By the American Revolution in 1776 Spain claimed essentially all land west of the Mississippi River.  Mexico’s independence from Spain in 1821 gave it jurisdiction over the Southwest until the conclusion of the Mexican War in 1848.  The Treaty of Guadalupe Hidalgo transferred land in what is now California, Nevada, Arizona, New Mexico, Utah, and Colorado to the United States. What is now Idaho, Oregon, Washington, and part of Montana and Wyoming was acquired from Great Britain in 1846. Russia established settlements in what is now Alaska, Northern California, and Hawaii.  Until the Louisiana Purchase in 1803 part of what is now Montana, Wyoming, and Colorado was French, but was originally claimed by Spain. 


There were so many boundary and government changes for the Western States, the first step in research is to determine jurisdiction:  Spain, Mexico, Great Britain, France, Russia, the Republic of Texas, or United States territory or state. After 1848 this region was under control of the United States (except for a southern sliver of Arizona and New Mexico), but remember—territorial government preceded state government. Be aware that in the 1850s territorial boundaries encompassed large areas—greater than what would finally be defined in statehood.  If a locality and time period can be identified for an ancestor, determine which country, territory, or state had jurisdiction by using:

lib.utexas.edu/maps/national_atlas_1970/ca000103.jpg  and mapofus.org/united-states

Once a territory became a state, territorial records were archived with the federal government, and record-keeping on a state level began.  Find territorial records in NARA regional archives, or microfilmed copies at State Archives, university collections, and the Family History Library.  FHL has NARA microfilm—keyword search “Territorial papers.”


Because traditional records may not exist in the West, these record groups are essential:   1.  Maps—historical boundaries, topographical, cadastral, Spanish and Mexican land grants,  2. Land and property—land entry files, tract books, deeds, mining records,  3. Church records, 4.  Congressional records—U.S. Congressional Serial Set, bills and resolutions, Journals of Congress,  5.  Newspapers—frontier and mining,  6.  Court—disputes over water rights, boundaries, mining claims, territorial lawlessness,  7. Bureau of Indian Affairs (BIA)—White settlers interacted with Indigenous peoples regularly and Indian Agents sent frequent reports to headquarters, 8.  Diaries and journals—pioneers chronicled their journeys and traveled in groups.


Find repositories in FamilySearch Wiki “[state name] Archives and Libraries”, and in ArchiveGrid (see link below).  NARA facilities for Western States:  Riverside, CA (AZ, Southern CA, Clark County, NV); Denver, CO (CO, MT, NM, ND, SD, UT, WY) Seattle, WA (ID, OR, WA); San Bruno, CA (Northern CA, NV except Clark County, NV).


Find migration routes in FamilySearch Wiki:  Search for “[state name] Migration”


Identify dates for mineral strikes in your state.  Search in county archives, state archives, state departments of mines, the GLO/BLM online database, and university collections.


TribalFrontier military/forts
Colonization by other countriesFederal land acts
TrappersEnd of the Civil War
MinersReligious groups


all markers  usgs.gov/core-science-systems/ngp/board-on-geographic-names

  • HistoryGeo.  historygeo.com/ Original land ownership maps
  • Library of Congress.  Geography and Map Division. Land Ownership Maps.

Washington, D.C.: L.O.C., 1983.  2010 FHL microfiches:  First fiche #6079238;

Checklist: 6048262.  [covers 1840-1900] loc.gov/maps/?q=land+ownership



  • Utah State Archives. “Mining Claims Research Guide,”



Beers, Henry P.  Spanish and Mexican Records of the American Southwest: A Bibliographic Guide to Archive and Manuscript Sources.  Tucson:  U of A Press, 1979.

Billington, Ray Allen. Westward expansion: a history of the American frontier.  New York: Macmillan Publishers Limited, c1982.

Flanders, Stephen A. Atlas of American Migration. New York:  Facts on File, 1998.

Hart, Herbert M. Old Forts of the Southwest. New York: Bonanza Books, 1964.

Hayes, Derek.  Historical Atlas of the American West. Berkeley: UC Press, 2009.

Hill, Edward E., comp. Records of the Bureau of Indian Affairs. Washington, D.C.:  NARA, 1965.

Hone, E. Wade. Land and Property Research in the United States.  Salt Lake City: Ancestry, 1997.

Kvasnicka, Robert M. comp. The Trans-Mississippi West 1804-1912. Part IV, A Guide to Records of the Department of the Interior for the Territorial Period, Washington, D.C.: NARA, 2007.

Morrow, William W. Spanish and Mexican Private Land Grants. San Francisco: Bancroft-Whitney Co., 1923.

Swanton, John R.  Indian Tribes of North America.  Washington, D.C.: Smithsonian Inst. Press, 1952.

Twitchell, Ralph E. Spanish Archives of New Mexico. V. 1-2. Cedar Rapids: Torch Press, c1914.

United States Congressional Serial Set.  Washington, D.C.: U.S. G.P.O. [Began with: No. 1, with the 15th Congress, 1st session, 1817]

Wexler, Alan.  Atlas of Westward Expansion. New York:  Facts on File, 1995.

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