 In large part due to Limbert 's work , Craters of the Moon National Monument was proclaimed on May 2 , 1924 by U.S. President Calvin Coolidge to " preserve the unusual and weird volcanic formations " . The Craters Inn and several cabins were built in 1927 for the convenience of visitors . The Mission 66 Program initiated construction of today 's road system , visitor center , shop , campground and comfort station in 1956 and in 1959 the Craters of the Moon Natural History Association was formed to assist the monument in educational activities . The addition of an island of vegetation completely surrounded by lava known as Carey <unk> ( air photo ) increased the size of the monument by 5 @,@ 360 acres ( 22 km2 ) in 1962 . 
