Since the Communist victory in 1949, Beijing has become a great industrial area, the heart of a vast complex of textile mills, iron- and steelworks, railroad repair shops, machine shops, chemical plants, and factories manufacturing heavy machinery, electronic equipment, locomotives, plastics, synthetic fibers, and rolling stock. With the construction in the 1970s of a pipeline that links the city with the Daqing oil fields, Beijing has developed a sizable petrochemical industry. Service industries also grew. New industrial development declined in the 1970s and 80s, mainly due to concerns over further pollution. The city is a rail hub, receiving lines from all sections of the country and linked directly with Vietnam and, through both Mongolia and NE China, with Russia. Its airport, greatly expanded in 1999, links it to all major Chinese cities and numerous foreign countries.