Prior to 1861, the area now known as Larimer County was a part of the Nebraska Territory. Larimer County was created by an act of the first Territorial Legislature of Colorado, approved November 1, 1861. The County as created was bounded on the north by Wyoming; east by Weld County; south by Boulder and Summit Counties; and west by the Snowy range or Continental Divide (including North Park).
Larimer County, as originally created, was ninety (90) miles long and fifty-one (51) miles wide at its widest part, the width varying according to the trend of the mountains on its western boundary, and contained approximately 4,300 square miles of territory, or 2,752,000 acres. In 1874 Grand County was carved out of Summit County and its northern boundary formed a part of the southern boundary of Larimer County. Even though the area known as North Park was not affected by this change, local officials assumed differently and, therefore, enumerated it as part of Grand County in the 1880 and 1885 censuses.
No further change was made in the Larimer County boundaries until the Seventeenth General Assembly of Colorado, in the winter of 1909, created Jackson county out of that portion known as North Park, reducing the overall size of Larimer County to approximately 2,800 square miles, or 1,792,000 acres.
At the time Larimer County was originally created, La Porte was named as the county seat. But at an election held in 1868, the county seat was moved to Fort Collins by a vote of the people of the County.
Colorado Counties Map
Larimer County Map, 1901
Township Map of Larimer County, Colorado.
It was based on an 1899 map.