Jefferson county is part of the Upper Snake River Valley in southeast Idaho. Rigby is the county seat. Other communities are Annis, Barlow, Bassett, Camas, Clark, Garfield, Grant, Hamer, Heise, LaBelle, Lewisville, Lorenzo, Menan, Midway, Monteview, Mud Lake, Ririe, Roberts, and Terreton. Its chief industries include farming and the Idaho National Engineering Laboratory under the direction of the U.S. Department of Energy. It covers 1,106 square miles.
It was established February 18, 1913, from Fremont county. It was named for Thomas Jefferson, third president of the United States. Rigby was named for William Rigby who was greatly responsible for bringing the railroad into the Upper Valley. Its most famous citizen was Philo T. Farnsworth who was the first inventor of television while still a student at Rigby High School.
From the Sugar City Times, Thursday, November 20, 1913
Proclamation Creating the New Counties
"Whereas, the legislature of the state of Idaho, at its Twelfth regular session, passed a certain act known as Chapter 25, session laws, 1913, wherein the county commisioners of Fremont county were authorized and directed to call an election for the purpose of submitting the boundaries described in section 2 of the said act, the question of whether the territory included within the boundaries should be created into a new county to be known as Jefferson county, and the further question of deciding, should the proposition to create same carry at the said election and
"Whereas, the said board of county commissioners did in pursuance of the said act call an election for the purpose of determining the questions hereinbefore stated, which said election was duly held on the fourth day of November, 1913, due notice having been given by publication and posting of notices as required by the said act, and
"Whereas, it appears by the certificate of the said board of county commissioners of the said Fremont county that they did on the tenth day of November, 1913, canvass the votes cast at the said election held as aforesaid, and
"Whereas, it appears from the canvass and the said certificate of the board of county commissioners of Fremont county that 2412 votes were cast at said special election, that 1825 votes were cast 'in favor of Jefferson county', that 587 votes were cast 'against Jefferson county', that 1376 votes were cast for Rigby for the county seat of Jefferson county, and that the village of Rigby received 403 votes for county seat of Jefferson county more than any other incorporated city, town or village;
"Now, therefore, I, John M. Haines, governor of Idaho, do hereby proclaim as required by the said act, the creation od said county of Jefferson and the selection of Rigby as the county seat of such county, the seperate existence of said county to take effect on the first day of january, 1914, the date fixed by the said act for the officers to be apponted for Jefferson county to qualify and commence their duties.
"In witness whereof, have hereunto set my hand and caused the great seal of the state of Idaho to be affixed this twelfth day of November, in the year of our Lord, one thousand nine hundred and thirteen,
"John M. Haines,
Governor.
"By the Governor:
"W.L. Gifford,
"Secretary of State."
