The United States acquired the area of Idaho through a treaty with Great Britain in 1846. Idaho Territory was organized from parts of Dakota, Nebraska, and Washington territories on March 3, 1863, and included parts of present-day Montana and Wyoming. Its area was reduced in 1864 by the organization of Montana Territory and again in 1868 by the organization of Wyoming Territory, to generally the same boundary as the present state. Idaho was admitted to the Union on July 3, 1890, as the 43rd state.
Census data for Idaho are available beginning with the 1870 census. The portion of Yellowstone National Park in Idaho was probably enumerated as part of Wyoming from 1880 to 1910. The area was shown as a separate county equivalent in the census reports for Idaho from 1920 to 1960. The portion of the park in Idaho was legally added to Fremont County before the 1970 census.
Data for the legally established state of Idaho are available beginning with the 1900 census. The census day for the 1890 census was June 2, 1890.
See: Geographic Terms & Concepts
Counties & County Equivalents
There are 44 counties in Idaho. All counties are functioning governmental units, each governed by a board of commissioners.
Interactive Map of Idaho Counties | Static Overview Map of Idaho Counties
There are 170 county subdivisions in Idaho. They are all census county divisions (CCDs), which are delineated for statistical purposes, have no legal function, and are not governmental units.
Places (Incorporated Cities, Towns & Census Designated Places)
Idaho has 227 places; 201 incorporated places and 26 census designated places (CDPs). The incorporated places are all cities. Lost River city is governmentally inactive.
Alphabetical List of Cities, Towns, CDPs and Other Populated Places
A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q, R | S | T | U, V | W, X, Y, Z
Idaho Civil Features
Idaho Civil Features: Political Subdivisions, Native Areas, Land Grants, etc. - sorted by Census Class Codes.
Metropolitan and Micropolitan Stastical Areas
There are 5 Metropolitan and 8 Micropolitan Statistical Areas in Idaho. ID Metopolitan & Micropolitan Areas
Idaho ZIP Code Tabulation Areas
There are 285 ZIP Code tabulation areas (ZCTAs) in Idaho. View Idaho ZIP Codes and ZIP Code Maps.
Idaho has 115 unified school districts. View Idaho Public and Private Schools.
Idaho has 2 congressional districts. An interactive map shows the contact information for each Representative as well as the boundaries for each Idaho district. View Map of Idaho Congressional Districts.
State Legislative Districts
There are 35 state senate districts and 35 state house districts in Idaho.
American Indian Areas
Idaho has five federally recognized American Indian reservations; two with associated off-reservation trust land.
Other Information Of General Geographic Interest
A portion of Yellowstone National Park is located in Fremont County. The remainder of the park is located in Montana and Wyoming. Prior to the 1970 census, Yellowstone National Park was an entity separate from any county government.