Littleton is the Home Rule Municipality in Arapahoe, Douglas, and Jefferson counties that is the county seat of Arapahoe County, Colorado, United States. The city is a part of the Denver-Aurora-Lakewood, CO Metropolitan Statistical Area. The city population was 41,737 at the 2010 United States Census, ranking as the 20th most populous municipality in the State of Colorado.
The city of Littleton's history dates back to the 1859 Pike's Peak Gold Rush, which brought not only gold seekers, but merchants and farmers to the community. Richard Sullivan Little was an engineer from New Hampshire who made his way out West to work on irrigation systems. Little soon decided to settle in the area at present day Littleton and brought his wife Angeline out from the East in 1862. The Littles, along with many neighbors, built the Rough and Ready Flour Mill in 1867, which provided a solid economic base in the community. By 1890, the community had grown to 245 people and the residents voted to incorporate the Town of Littleton.
Littleton grew significantly throughout the 1950s and 1960s due to its proximity to Martin Marietta facilities, which produced the Titan rocket and other aerospace products.
Littleton twinned with Bega, Australia in 1961 as one of the earliest sister cities.
Littleton became widely known in 1999 when the Columbine High School massacre occurred at Columbine High School, where two of the school's students, Eric Harris and Dylan Klebold, murdered 12 students and one teacher, injured 24 others and then killed themselves.