United States Government Forest 110 N Wabash Ave, Glendora, CA91741 The Angeles National Forest covers more than 36,000 acres of rugged terrain, ranging in elevation from 1,600 to 8,200…More feet. Glendora is home to numerous hiking trails and several parks and campgrounds in the Angeles National Forest. The San Gabriel River Ranger District in Glendora is one four service offices in the region. Information on the various nature trails, campgrounds and parks may be obtained at this office. Call for more information.