The Spanish expedition of Dominguez–Escalante of 1776 reached just south of what would be Moffat County and noted the area and inhabitants, but did not offer detailed information.

[4] John C. Freemont would lead the first organized exploration of Moffat County on his return from California during his second expedition.

In 1879, a new agent, Nathan Meeker, was appointed to serve at the White River Agency in northwestern Colorado.

Meeker had founded a Christian-based European agricultural colony in 1870 in eastern Colorado and had strong ideas of how a community should be structured.

His efforts to impose an agricultural lifestyle on the native people created a conflict that ultimately led to the murder of Meeker and all of the staff at the Agency.

After the removal of the Ute tribes, the U.S. government opened up northwestern Colorado for mining, commercial cattle ranching, and homesteading.

David Moffat had been the primary force driving the establishment of a railroad from Denver to Salt Lake City.

[8] The railroad was important for cattle ranchers in Moffat County's early years; however, the track was never extended into Utah.

Then Colorado Governor and former Moffat County resident, Edwin C. Johnson lobbied for I-70 to continue through Denver and connect to Salt Lake City.

[citation needed] The population in Moffat County stabilized at just over 5,000 people by the first census in 1920; however, it remained stagnant until the 1970s when construction of three coal-fired electrical power plants began.

The 2020 census data showed the population at 13,292 people, which is almost the same as the county's post-power plant boom in the 1980s.

In gubernatorial elections, Moffat County has also generally been Republican, but was nonetheless carried by Democrat Roy Romer by a narrow margin in 1990[21] – when he carried all but four counties statewide – by Dick Lamm in 1982[22] and by Constitution Party candidate Tom Tancredo in 2010.