Fort Collins began life as a military fort in 1864. The National Institute of Standards and Technologies runs two radio stations here devoted to the broadcast of standard time: WWV, built in 1923; and WWVB, built in 1956.
According to the United States Census Bureau, the city has a total area of 122.1 km² (47.1 mi²). 120.5 km² (46.5 mi²) of it is land and 1.6 km² (0.6 mi²) of it is water. The total area is 1.27% water.
As of the census of 2000, there are 118,652 people, 45,882 households, and 25,785 families residing in the city. The population density is 984.4/km² (2,549.3/mi²). There are 47,755 housing units at an average density of 396.2/km² (1,026.0/mi²). The racial makeup of the city is 89.63% White, 1.02% African American, 0.60% Native American, 2.48% Asian, 0.12% Pacific Islander, 3.61% from other races, and 2.53% from two or more races. 8.77% of the population are Hispanic or Latino of any race.
There are 45,882 households out of which 29.0% have children under the age of 18 living with them, 44.9% are married couples living together, 7.9% have a female householder with no husband present, and 43.8% are non-families. 26.0% of all households are made up of individuals and 5.9% have someone living alone who is 65 years of age or older. The average household size is 2.45 and the average family size is 3.01.
In the city the population is spread out with 21.5% under the age of 18, 22.1% from 18 to 24, 31.5% from 25 to 44, 17.0% from 45 to 64, and 7.9% who are 65 years of age or older. The median age is 28 years. For every 100 females there are 100.9 males. For every 100 females age 18 and over, there are 99.7 males.
The median income for a household in the city is $44,459, and the median income for a family is $59,332. Males have a median income of $40,856 versus $28,385 for females. The per capita income for the city is $22,133. 14.0% of the population and 5.5% of families are below the poverty line. Out of the total people living in poverty, 8.3% are under the age of 18 and 5.8% are 65 or older.