From its earliest park in 1913, the County of San Diego has more than 100 years of serving the public with unique park and recreational experiences while preserving significant natural and cultural resources. Officially, the San Diego County Board of Supervisors established the Department of Recreation in 1946. Today, the department manages over 50,000 acres of parks, campgrounds, trails, recreation centers, sports complexes, and ecological and open-space preserves. The county covers an area that includes coastline, mountains, deserts, lakes, lagoons, and other habitats—it is the nation's most biologically diverse county—and the department's properties mirror this biodiversity. They also contain sites that reveal the county's history: Mexican-era ranchos, an overland stage station, remnants of an early gristmill, Victorian mansions, traces of flume systems, Depression-era construction projects, an 1887 boathouse, and parks that reflect the advent of early automobile tourism.