Robert Moran, one-time mayor of Seattle and shipbuilder, presented the original 2,600 acres to Washington State in 1920. By 1928, he had added another thousand acres to his original gift, and the park has been enlarged by various means of acquisition until in 1991 it has grown to its present 5,175.51 acres. In the mid-thirties, the Civilian Conservation Corps built many of the trails, roads, bridges and buildings now in use. Perhaps the most outstanding structure in the park is the stone tower atop Mt. Constitution, which affords a 360 degree view of the San Juans, the Cascades, the Olympics, and Northern Puget Sound. Rainfall averages 29.18 inches a year.