Founded in 1894 in Flagstaff, Arizona, by Percival Lowell, Lowell Observatory became one of the oldest observatories in the United States and was chosen for its elevation, dark skies, and railroad access. Created from Lowell’s interest in Mars and planetary study, it later achieved lasting fame through the search for Planet X, when Clyde Tombaugh identified Pluto there in 1930. The observatory also made major contributions through Vesto Melvin Slipher’s spectroscopic research, work supporting Apollo-era lunar mapping, and observations by Vera Rubin and Kent Ford that confirmed dark matter. It remains an active research center and public observatory.