Query: How many acres of land does Houston's green spaces cover?
Context: Of the 10 most populous U.S. cities, Houston has the most total area of parks and green space, 56,405 acres (228 km2). The city also has over 200 additional green spaces—totaling over 19,600 acres (79 km2) that are managed by the city—including the Houston Arboretum and Nature Center. The Lee and Joe Jamail Skatepark is a public skatepark owned and operated by the city of Houston, and is one of the largest skateparks in Texas consisting of 30,000 (2,800 m2) square foot in-ground facility.