Dade City was named the temporary county seat until a popular vote was held in 1889, at which time voters made Dade City the permanent county seat. As early as 1917, residents of the western part of the county proposed forming a separate county or merging with Pinellas County, as Dade City was not centrally located in the county. The issue was finally resolved in the late 1970s with the construction of identical government centers in both Dade City and New Port Richey.
The earliest towns were Anclote, Blanton, Dade City, Earnestville, Fort Dade (not to be confused with Fort Dade on Egmont Key), Macon (Trilby), Lacoochee, St. Leo, and San Antonio. Citrus was an important industry when the county was formed, although a decline followed a freeze in 1895. Several large sawmills operated in the county in the early part of the 20th century.
During the Florida land boom of the 1920s, New Port Richey became the winter home of silent screen star Thomas Meighan and golfer Gene Sarazen; Meighan attempted to bring other Hollywood figures to the city. The county has experienced significant population growth since the 1960s. The growth began along the Gulf coast but is now occurring most rapidly in areas north of Tampa.