Clinton Hart Merriam was born in upstate New York on 5 December 1855. His family was a wealthy, successful family with a large estate surrounded by forests brimming with a variety of plants and animals. This atmosphere allowed Merriam to spend many hours in the woods, exploring the local flora and fauna. This early exposure encouraged Merriam to have a deep appreciation for nature.

Merriam was educated at Yale University and studied human anatomy. This education culminated in completing medical school and becoming a physician. Many early naturalists were in the medical profession, and Merriam used this time to go on field studies and collect vast amounts of biological information. At the age of 18, he published his first summaries of his biological studies.

In 1886, Merriam began work for the United States Department of Agriculture in the Entomology Division. He used this platform to promote in-depth biological surveys of the United States. Merriam felt this would discover new organisms in America and eventually lead to biogeographical studies, investigating interactions between biota and abiotic elements such as temperature and elevation.

Merriam first visited the Colorado Plateau in 1889 while on the Arizona Territory San Francisco Mountain Region Survey for the USDA. He chose this region to investigate biogeographical interactions because "different climates and zones of animal and vegetable life succeed each other from base to summit" and "because of its southern position, isolation, great altitude, and proximity to an arid desert." Merriam trekked greatly around and on the San Francisco Peaks, including the cinder hills, Walnut Canyon, Grand Canyon, and the Painted Desert. His expeditions included extensive plant and animal collections and elevation documentation from an aneroid barometer. These studies eventually supported his Life Zones concept of biogeographical elevation gradients.