Yes.
The city of Aspen voted to add fluoride to its drinking water in 1968.
Fluoride is a compound found naturally in soil, food, plants, animals and the human body. Almost all water contains some naturally occurring fluoride, but usually at levels too low to prevent cavities.
The recommended fluoride concentration in drinking water is 0.7 milligrams per liter. This is about equal to 3 drops of water in a 55-gallon barrel.
The highest concentration allowed under Environmental Protection Agency rules is 4 milligrams per liter. Fluoride consumed in excess of that over many years could cause bone disease.
The Centers for Disease Control and Prevention says 72.7% of the U.S. population receives supplemental fluoride in their drinking water. That number is 75.2% in Colorado, making it 28th among states when ranked by the percentage of their populations using fluoridated water.
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