Idaho Genealogy Research Guide

by Andrew Koch

When Lewis and Clark’s expedition entered modern Idaho after crossing the Continental Divide in 1805, they became first documented European Americans to do so. “We proceeded on to the top of the dividing range,” Lewis wrote, “from which I discovered immense ranges of high mountains still to the west of us.”

That scenic view Lemhi Pass, now a registered landmark, opened explorers to Idaho, the “gem of the mountains” that lives up to its nickname. Read on for some key moments in Idahoan history, plus the best online records and resources for genealogists to consult when searching for ancestors there.

Idaho Genealogy Research Guide Contents

Idaho Genealogy Fast Facts


Part of Oregon Territory, 1848; part of Washington Territory, 1859; Idaho Territory, 1863




1850, 1860, 1870; 1860 and 1870 Cache County, UT census (contains some southern Idaho); reconstructed 1890 census









State History

Because of its mountainous terrain, Idaho was one of the last areas of the continental United States to be explored by Europeans. It wasn’t until Lewis and Clark’s expedition in 1805 that Europeans ventured into the Snake River Valley and its surroundings. At the time, the region was inhabited by thousands of American Indians, notably the Bannock, the Nez Perce, the Coeur d’Alene, and bands of the Shoshone (such as Lemhi and Tukudeka) and Northern Paiute.


Idaho was part of the “Oregon Country,” a swath of land claimed by both the United States and the United Kingdom. In 1818, the two nations agreed to jointly occupy and settle the region, and the 1846 Oregon Treaty established the 49th parallel as the border between the two nations.

The next few decades saw fur traders and missionaries become active in the area, with organizations such as the Hudson’s Bay Company and the North West Company dominating trade in the Snake River region. Missionaries from the Church of Jesus Christ of Latter-day Saints, in particular, made excursions from neighboring Utah north to the region.

Congress created the Oregon Territory in 1848, which then included Idaho, Oregon, Washington, and parts of Montana and Wyoming. The area was split into Oregon (south) and Washington (north) Territories a few years later, only to be reorganized again as Washington Territory after Oregon became a state in 1859.

Settlers and fortune-seekers alike passed through Idaho on their way to Oregon and California. But Idaho became a destination in its own right when gold was discovered there in 1860. Idaho became a territory three years later, briefly including modern Montana and Wyoming (before each of those became separate territories).

An increase in the presence of miners and settlers in the 1860s led to more conflict with local American Indians, with the Bear River Massacre (1863), the Snake War (1864–1868), and the Nez Perce War (1877) among the bloodiest. Despite this, Idaho’s population swelled from 17,000 in 1863 to 90,000 in 1890 (when Idaho became a state). Notable settlement groups included the English, German, Irish and Basque (from Spain).

Since then, Idaho has become known for its beautiful landscapes; mining and technology industries; and (of course) the potato crop.

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State Timeline


Lewis and Clark reach the Idaho region through Lemhi Pass
In a treaty, the United States and United Kingdom agree to jointly administer the “Oregon Country,” including modern Idaho


Forts Boise and Hall are established, primarily as trading posts
The United Kingdom cedes all land south of the 49th parallel to the United States


Latter-day Saint pioneers found Franklin, the first permanent European American settlement in modern Idaho
Gold is found in Boise; this and other discoveries in Idaho lead to an 1860s gold rush
The Territory of Idaho is formed; Boise is incorporated as a city and a new Fort Boise is established


Idaho becomes the 43rd state to join the Union
“The Big Burn” wildfire destroys 3 million acres in Idaho and Montana
Caribou, Clark and Jerome Counties are created, the last major change to Idaho’s county borders

Historic Map

Territory of Idaho. 1876. Entered 1879 by S. Augustus Mitchell. Washington. 1880. (David Rumsey Map Collection)

Idaho Genealogy Records Online

Vital Records

A relatively new pioneer state, Idaho had spotty vital records collection until well into the 20th century. The state didn’t mandate birth and death records until 1911, and didn’t keep state-level marriage records until 1947. And even those are under privacy restrictions: 100 years for birth records and 50 for marriage and death records. Only immediate family members can request them. You can order eligible records from the state health department’s vital records office .

Fortunately, there are workarounds. Counties kept their own records: births and deaths in 1907 or earlier, and marriages in 1895 or earlier. Any surviving county-level records will reside in the respective county recorder’s office.

The Idaho State Historical Society has compiled information from county-level vital records (as well as community histories and newspapers) into an Idaho Biographical Index. You can access it via a Google Sheets link at

In addition, Brigham Young University—Idaho (BYU-Idaho) hosts a free Western States Marriages Index, which includes data from more than 900,000 county marriage records throughout the American West. The school also has created an index of death records from 1911 to 1951.

FamilySearch and Ancestry. com each have collections of Idaho birth, marriage and death indexes, some linked to images. Consult each site’s collection list to see what’s available.

Land Records

Since Idaho is a public-land state, the US government surveyed and distributed its land directly to settlers. The first land offices opened between 1866 and 1870, and they kept tract books and township plats for the area. Applicants filed paperwork with these local offices, but it was the federal General Land Office in Washington, DC, that issued land actual patents. The US Bureau of Land Management has an index of patents online , and you can find an index of tract books at FamilySearch .

Once land was in private hands, it was passed between individuals via deeds, mortgages and other transactions managed by the county clerk offices. You can find pre-1900 records at the Idaho State Archives and the Family History Library, while later records are at individual county clerk offices.

If you need to review how Idaho’s borders changed over time, consult historical maps from the Idaho Genealogical Society, and the Atlas of Historical County Boundaries. The Idaho Genealogical Society also has a list of each of Idaho county and its foundation date, plus a brief history.

Census Records

In theory, Idaho first appeared in the federal census in 1850 as part of Oregon Territory. But in practice, enumerators didn’t log any residents there in that census or the 1860 census. The Territory of Idaho does, however, appear in the 1870 census.

The Idaho State Historical Society created a database that attempts to reconstruct the missing 1890 federal census using other available records, such as vital records and newspapers. The society also has links to the 1870 and 1880 supplemental schedules.

Idaho didn’t take any of its own state or territorial censuses. But if you have American Indian ancestors in the region, you can look to microfilmed Indian censuses on FamilySearch beginning in the 1880s.

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Military Records

Idaho was not yet a state at the time of the Civil War, and no major battles took place there. However, many Civil War veterans migrated to the state. One of the Idaho State Historical Society’s searchable collections contains information about these veterans living in the state, compiled from various sources. Pension records (index available at FamilySearch) or the Civil War Soldiers and Sailors System can provide more information about them.

If your ancestor fought in conflicts with American Indians in the 1800s, check for him in FamilySearch’s collection of Army “regulars” from 1798 to 1914.

State Publications and Resources


City directories place residents in a specific place at a specific time, especially useful if census records are missing or in years between federal enumerations. FamilySearch has 20th-century directories for Boise, Coeur d’Alene and Pocatello.


The state archives has Idaho newspapers dating back to 1863, and has partnered with the Library of Congress’ Chronicling America project to make them searchable online.

Other notable newspaper collections include and GenealogyBank. LDS Genealogy has a roundup of Idaho newspapers and obituaries at major sites such, plus dedicated pages for each of Idaho’s 44 counties. The Boise Public Library also has an online index of obituaries published in The Idaho Statesman from 1957 to 2017.

Idaho Genealogy Resources


Cyndi’s List: Idaho

FamilySearch Research Wiki: Idaho

Idaho Genealogy

IDGenWeb Project

Linkpendium: Idaho

Mountain West Digital Library

Western States Marriage Index


History of Idaho by Leonard J. Arrington (University of Idaho Press)

The Idaho State Historical Society Reference Series by Merle Wells

Idaho’s Place: A New History of the Gem State by Adam M. Sowards (University of Washington Press)

In Mountain Shadows by Carlos Arnaldo Schwantes (University of Nebraska Press)


Archives West

Brigham Young University—Idaho (BYU-Idaho) Library

Idaho Bureau of Vital Records and Health Statistics

Idaho Genealogical Society

Idaho State Historical Society (and Archives)

National Archives at Seattle

University of Idaho Library: Special Collections & Archives

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