Mailbox Peak is a 4,841-foot mountain in Washington’s Cascade foothills east of North Bend, notable for its dramatic rise above the Snoqualmie valleys and for the summit mailbox that gave it its common name, though that name is not officially recognized by the U.S. Board on Geographic Names. Its waters drain toward both the South Fork and Middle Fork Snoqualmie River. Known for a demanding trail that gains about 4,100 feet, it was long infamous for an even steeper old route used as a conditioning test by mountaineers and fire academy recruits. Its popularity, however, has also made it a frequent site for search and rescue incidents.