A sawmill town, it was named for the many deer that wintered there in pioneer days. A post office was established at Deer Park on June 7, 1890 and was moved south on June 13, 1891.
In the 1880s, the broad valley surrounding Deer Park was a virgin forest of pine, fir, and tamarack. The construction of a Great Northern R.R. branch from Spokane to Deer Park in 1884 stimulated exploitation of the rich resources of the region. Since then, lumber companies and farmers have steadily cut the timber line back to the mountains. Large deposits of fire clay, kaolin, and mineral pigment were found within a short distance of the town. It was an important shipping point for lumber, grain, and fruit.
Deer Park has remained a primarily residential and agricultural community, although it promotes tourism by hosting several events throughout the year, including the Deer Park Fair and Rodeo. The surrounding area is also popular with outdoor sports enthusiasts, with seven fresh-water lakes within a radius of 20 miles, each offering swimming, fishing, and boating. Deer Park Golf and Country Club has an eighteen-hole course.