Henderson is a city in Clark County, Nevada, United States, about 16 miles (26 km) southeast of downtown Las Vegas. It is the 2nd most populous city in Nevada, after Las Vegas, with 317,610 residents. The city is part of the Las Vegas Valley. Henderson is notable for its extensive system of outdoor recreation facilities, including over 220 miles (354 km) of trails and 72 parks. Incorporated in 1953, Henderson was originally known for its role in magnesium production during World War II. Since then, it has grown rapidly through the development of master planned communities starting with the large Green Valley neighborhood, redevelopment and reinvestment after the PEPCON Disaster, and the city government's historically proactive planning and management.