

STATE OF IDAHO 1900-19
| 1900 | Idaho population: 161,772. New York Canal completed. Democrats, Silver Republicans and Populists arrange party fusion for 1900 election. Idaho State Dairymen's Association organized. Idaho Falls incorporated. |
| 1901 | The Free Traveling Library (now known as the Idaho State Library) established. The Academy of Idaho (now Idaho State University) opens in Pocatello. |
| 1902 | After concluding that Diamondfield Jack Davis had been convicted by mistake, in a case growing out of the most notable incident of the Idaho sheep and cattle wars, the State Board of Pardons turned him loose. National Reclamation Act passed, provides for federal aid for irrigation. |
| 1903 | Idaho's hunting and fishing licensing system began. The Idaho Industrial Training School founded at St. Anthony as a reform school for children. First Carey Act land opening at Shoshone. Miller Dam on Snake River opens Twin Falls area to irrigated farming. President Theodore Roosevelt plants maple tree on capitol grounds. |
| 1904 | City of Twin Falls platted. Chief Joseph dies September 21. |
| 1905 | Construction of a new capitol building in Boise authorized at a cost of $1,000,000. Insane asylum established at Orofino. The first train arrives at Twin Falls August 7. Sawtooth National Forest created. Former Governor Frank Steunenberg assassinated December 30. |
| 1906 | Steunenberg assassin Harry Orchard implicates three leaders of the Western Federation of Miners in the plot. The largest sawmill in the United States begins operation at Potlatch. Pioneer Monument at capitol grounds erected. "Steward Decree" adjudicates water rights along the Boise River. |
| 1907 | William E. Borah elected to the U.S. Senate, where he gains an international reputation during thirty-three years of service. William D. Haywood is found not guilty of conspiracy and the assassination of Frank Steunenberg, at the end of an internationally celebrated trial, Harry Orchard sentenced to life in prison for the assassination. Idaho State Flag adopted. Idaho Historical Society founded. Bonner and Twin Falls County created. |
| 1908 | The Idaho revised code published. Under President Roosevelt's forest reserve policy, one-half of the state is organized into National Forest reserves. Lake Lowell completed . Idaho adopts direct primary and local option over regulation of liquor. Minidoka Dam completed. State Parks established at Heyburn, Shoshone Falls, and Payette Lake. Allotment of Coeur d'Alene Indian Reservation. Provisions for rural high school districts established. |
| 1910 | Idaho population: 325,594. Devastating forest fire consumes 1/6 of north Idaho's forests, destroying many communities. State banking and highway district laws enacted. Buckeye tree planted on the capitol grounds by President William Howard Taft October 9. Search and seizure law enacted for enforcing liquor laws. Idaho State Sanitarium (now known as the Idaho State School and Hospital) located at Nampa. Adams, Bonneville, Clearwater and Lewis counties created. Revised revenue laws enacted, providing a new system of assessment, equalization, levy and collection of taxes. Constitutional amendments adopted authorizing initiative, referendum, and recall. State Board of Education established to supervise all levels of education within the state of Idaho. |
| 1913 | Public Utilities Commission established. Northwest Nazarene College in Nampa founded. First motor vehicle laws enacted by the legislature. Comprehensive system of revenue for state, county, municipal and school purposes enacted. School for the Deaf and Blind opens in Gooding. Franklin, Gooding, Jefferson, Madison, Minidoka and Power counties created. |
| 1914 | Moses Alexander elected first Jewish governor in the United States. |
| 1915 | Arrowrock Dam completed. Columbia and Snake River improvements for navigation to Lewiston completed. Second Idaho Regiment of Infantry Volunteers organized into service at the call of President Woodrow Wilson for the Mexican Border War. The Academy of Idaho (now Idaho State University) becomes the Idaho Technical Institute. Idaho Horse and Cattle Association organized, later to become the Idaho Cattlemen's Association. Benewah, Boundary, Gem and Teton counties created. |
| 1916 | Constitutional amendment for statewide prohibition ratified. State highway program begins as part of the national good roads movement. |
| 1917 | Statewide prohibition goes into effect January 1. Workmen's Compensation System and State Insurance Fund established. Annual state fair established at Boise. Ricks Academy becomes a college and is accredited by the State Board of Education. Butte, Camas, Payette and Valley counties created. |
| 1918 | Non-Partisan League takes over Idaho Democratic primary September 3, subsequently Idaho's primary nominating system is abandoned for twelve years. |
| 1919 | Administrative consolidation enacted by legislature. Functions of fifty-one departments, boards and bureaus placed under nine administrative departments responsible to the governor. Bureau of Highways created to inaugurate a state highway system. Bureau of Constabulary organized May 18, with Department of Law Enforcement. First Music Week held in Boise. Lava Hot Springs established by Department of Public Welfare. City of Jerome incorporated. Jerome, Clark, and Caribou counties created. |