In the 1970s, energy industry corporations started making their move to Texas. Those companies that chose Houston ended up clustering on the city's west side where land was available for suburban office campuses. Other non-energy companies such as Sysco and the Gulf States Toyota Distributors are headquartered in the Energy Corridor as well. The district contains approximately 26 million square feet of office space and over 95,000 employees. Nearly 300 companies call the Energy Corridor home, such as BP America at Westlake Park, ConocoPhillips, Citgo, Technip USA, Becks Prime, and SBM Offshore USA. Though most of Energy Corridor thrives off Fortune 500 companies operating there, people who visit the region are often surprised to see how developers were able to combine industrialism and residential cohesively. Since most of the business complexes are home to corporate headquarters, a large number of those living and working in the Energy Corridor are mid to high-level employees, which is why you will find the largest number of unspoiled natural areas of any metropolitan region in the United States here in Houston. In addition to that, there are well-maintained bayous and reservoirs, 26,000 acres of lush parkland, and 50 miles of trails leading to various campuses throughout the district.