The Palmer Divide is a ridge 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...

 that separates the Arkansas River

Arkansas River

The Arkansas River is a major tributary of the Mississippi River. The Arkansas generally flows to the east and southeast as it traverses the U.S. states of Colorado, Kansas, Oklahoma, and Arkansas. The river's initial basin starts in the Western United States in Colorado, specifically the Arkansas...

 basin from the Missouri River

Missouri River

The Missouri River flows through the central United States, and is a tributary of the Mississippi River. It is the longest river in North America and drains the third largest area, though only the thirteenth largest by discharge. The Missouri's watershed encompasses most of the American Great...

 (via the Platte River

Platte River

The Platte River is a major river in the state of Nebraska and is about long. Measured to its farthest source via its tributary the North Platte River, it flows for over . The Platte River is a tributary of the Missouri River, which in turn is a tributary of the Mississippi River which flows to...

) basin. It extends from the Front Range of the Rockies in central Colorado, eastward toward the town of Limon.

It is named after William Jackson Palmer

William Jackson Palmer

William Jackson Palmer was an American civil engineer, soldier, industrialist, and philanthropist.-Overview:...

, the founder of Colorado Springs. It staggers along the county line between Douglas County

Douglas County, Colorado

Douglas County is the eighth most populous of the 64 counties of the state of Colorado, in the United States. The county is located midway between Colorado's two largest cities: Denver and Colorado Springs...

 and El Paso County

El Paso County, Colorado

El Paso County is the most populous of the 64 counties of the state of Colorado of the United States, now more populous than Denver County. The United States Census Bureau concluded that the county population was 622,371 in 2010. In recent years, the population had come closer to that of Denver...

. This divide separates the Denver metropolitan area from the Pikes Peak

Pikes Peak

Pikes Peak is a mountain in the Front Range of the Rocky Mountains, west of Colorado Springs, Colorado, in El Paso County in the United States of America....

 area. The elevation varies between 6,000 and 7,500 feet, with the divide's highest point at Monument Hill.

This uplifted area causes a slight increase in precipitation from the rest of eastern Colorado, resulting in it containing the Black Forest

Black Forest, Colorado

Black Forest is a census-designated place near Colorado Springs, Colorado, United States. The population was 13,116 at the 2010 census. Black Forest is named such for the high density of Ponderosa Pines located in a generally small area...

, a peninsula of trees surrounded by dryer grassland plains.

This terrain feature is the cause of several small scale, or microscale weather patterns, and can make a great difference in the weather between Denver and Colorado Springs. Although this elevation technically qualifies it for the foothills category, it does not parallel a mountain chain as foothills do. The Palmer Divide is perpendicular to the mountains. Due to the orientation of the Palmer Divide with respect to the eastern plains, the weather can be similar to the foothills during active weather with enhanced precipitation, especially during snowstorms. Cities and towns within the Palmer Divide include Castle Rock

Castle Rock, Colorado

The Town of Castle Rock is the county seat of Douglas County, Colorado, United States and is named for the prominent castle tower-shaped butte near the center of town. It is part of Colorado's Front Range Urban Corridor and is located roughly 28 miles south of Denver and 37 miles north of...

, Franktown, Elizabeth, Kiowa, Monument, Black Forest, Sedalia and Palmer Lake.