The South Fork South Platte River is a tributary of the South Platte River

South Platte River

The South Platte River is one of the two principal tributaries of the Platte River and itself a major river of the American Midwest and the American Southwest/Mountain West, located in the U.S. states of Colorado and Nebraska...

, approximately 45 miles (72.4 km) long, in central Colorado

Colorado

Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...

 in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. It is located near the headwaters of the South Platte in Park County, Colorado

Park County, Colorado

Park County is the 17th most extensive of the 64 counties of the State of Colorado of the United States. The county was named after the large geographic region known as South Park, which was named by early fur traders and trappers in the area. The geographic center of the State of Colorado is...

 and drains part of the intermontane grassland basin of South Park

South Park (Colorado basin)

South Park is a high intermontane grassland basin, approximately 10,000 ft in elevation, in the Rocky Mountains of central Colorado. It encompasses approximately 1,000 square miles around the headwaters of the South Platte River in Park County approximately 60 mi southwest of Denver...

. It forms the South Platte by its confluence with the Middle Fork South Platte River

Middle Fork South Platte River

The Middle Fork South Platte River is a tributary of the South Platte River, approximately long, located in central Colorado in the United States...

 in southern South Park.

It rises on the eastern flank of the Mosquito Range

Mosquito Range

The Mosquito Range is a high mountain range in the Rocky Mountains of central Colorado in the United States. The peaks of the range form a ridge running north-south for approximately 40 miles from southern Summit County on the north end, then along the boundary between Lake and Park counties...

, below Weston Pass north of Buffalo Peaks in the Pike National Forest

Pike National Forest

The Pike National Forest is located in the Front Range of Colorado, USA, west of Colorado Springs and including Pikes Peak. The forest encompasses 1,106,604 acres within Clear Creek, Teller, Park, Jefferson, Douglas and El Paso counties. The major rivers draining the forest are the South Platte...

. It descends through a short narrow gorge to the southeast, then turns east to emerge into the eastern side of South Park approximately 10 miles (16 km) south of the town of Fairplay

Fairplay, Colorado

The Town of Fairplay is a statutory town that is the county seat and the most populous town of Park County, Colorado, United States. Fairplay is located in South Park at an elevation of . The town is the fifth-highest incorporated place in the State of Colorado. The population was 610 at the...

. It turns south, skirting the base of the mountains and flowing along the eastern side of U.S. Highway 285, then turns east, winding in a course that roughly follows U.S. Highway 24. It joins the Middle Fork to form the main branch of the South Platte near the community of Hartsel

Hartsel, Colorado

Hartsel is an unincorporated town and a U.S. Post Office located in Park County, Colorado, United States. Hartsel was founded in 1880. Located at the geographic center of the state, it is often referred to as "The Heart of Colorado". The community's namesake is Samuel Hartsel, a local cattle...

.