Arapaho Glacier and Arapahoe Avenue were named for the Arapaho Indians who lived here at the time of white settlement. Though called Arapaho, they referred to themselves as "Inunaina," meaning "our people." 

Barker Dam in Nederland was named for school teacher Hannah Barker, who sold the land for the dam and reservoir project. 

Eldora was first established as a gold mining camp and was called Eldorado which means "the golden" in Spanish. When application was made for a post office the name was changed because the name had already been claimed by Eldorado Springs. 

Eldorado Springs became a summer resort run by the Fowler Family in 1904. Visitors rode the Interurban electric railway from Denver to enjoy the thermal springs. 

Erie was originally a coal mining camp and was named by Richard Van Valkenburg in 1873 for his hometown Erie, PA. Coal mining continued in Erie until 1978 when the Eagle Mine closed. 

Gold Hill - Thomas Aikens and his group of 15 gold seekers from Nebraska were the first white settlers to arrive in Boulder. They discovered gold at Gold Run near Gold Hill. By 1868 there were 25 gold mills in the area. The miners were hard-working and religious, voting to prohibit saloons in the camps. 

The town of Marshall was named after Joseph M. Marshall who discovered coal in the area. 

The Moffat Tunnel was named for David H. Moffat, president of the narrow-gauge Denver & Rio Grande Railroad. 

Nederland was at one time known as Middle Boulder, Brownsville, and also Tungsten Town. The Dutch owners of the nearby Caribou silver mines changed the name to Nederland which means "low land." The name was chosen because Nederland is lower than the mine at Caribou and is surrounded by mountains. Gold, silver, and tungsten were mined extensively around Nederland. 

Niwot Ridge was originally called Bald Mountain. The name now honors Chief Niwot of the Arapahos. Niwot worked for peace among whites and Native Americans. He died of wounds suffered in the Sand Creek Massacre. 

Rollinsville was a mining camp founded by John Q. A. Rollins. Rollins did not permit saloons, gambling houses or dance halls in the camp. 

Superior was founded in 1895 as a supply town for the Industrial Coal Mine. The name supposedly came from the claim that the coal mined there had "no superior in the state." 

Ward was named for Calvin W. Ward who established the Miser's Dream gold mine there in 1860. Mining of gold, silver, and other metals continued for the next 30 years. 
Caribou was named by George Lytle. He felt the country was similar to the Cariboo Mountains in Canada. The U.S. Post Office changed the spelling to Caribou.