The City of Delta is the county seat and the most populous city of Delta County, Colorado, United States. The population was 6,400 at the 2000 census. The United States Forest Service headquarters of the Grand Mesa, Gunnison, and Uncompahgre National Forests are located in Delta.
Delta is located at 38°44′27″N 108°3′48″W / 38.74083°N 108.06333°W / 38.74083; -108.06333 (38.740879, -108.063423).
According to the United States Census Bureau, the city has a total area of 5.5 square miles (14.3 km²), of which, 5.3 square miles (13.8 km²) of it is land and 0.2 square miles (0.5 km²) of it (3.62%) is water.