 Lewisville's rapid growth began when construction of the Garza–Little Elm Dam finished in 1954, expanding the Garza–Little Elm Reservoir into what is now Lewisville Lake.The city adopted a home rule charter for a council–manager style of municipal government in 1963, becoming one of only a few home rule cities in Texas with a population of less than 5,000.In September 1969, 13 days after Woodstock, the city hosted the Texas International Pop Festival, which drew over 150,000 spectators and featured performances by Janis Joplin, B.B.