During the 1960s, Chandler Robbins and his associates at the Migratory Bird Population Station (now the PAtuxent Wildlife Research Center) in Laurel, Maryland developed the concept of a continental monitoring program for all breeding birds. The roadside survey methodology was field tested during 1965, and the North American Breeding Bird Survey (BBS) was formally launched in 1966 when approximately 600 surveys were conducted in the U.S. and Canada east of the Mississippi River. The survey spread to the Great Plains states and prairie provinces in 1967. By 1968, approximately 2000 routes were established across southern Canada and the contiguous 48 states, with more than 1000 routes surveyed annually.