On June 15, 1916, President Woodrow Wilson signed a unanimously approved Congressional charter that allowed the group to be recognized under Title 36 as a "patriotic and national" organization. This charter, which came approximately six years after the Scouts were founded in 1910, established the group as America's one "true" scouting organization, providing the BSA with a national platform to recruit and eliminating the need to seek incorporation on a state-by-state basis.
http://www.csmonitor.com/USA/Society/2016/0615/Boy-Scouts-100-years-ago-vs.-now-What-s-changed