Oil and gas remain the largest industries in Calgary, which is home to large Canadian and global companies including BP, Shell Canada, Encana, TransCanada and Suncor Energy. Agriculture, hi-tech and service industries are also key to the city’s economy. Imperial Oil and Canadian Pacific Railway have located their headquarters here and are among Calgary’s largest employers, along with telecommunications giants Shaw Communications and Telus, Nova Chemicals and oil companies Nexen and CNRL. Calgary is also a destination for winter sports and tourism.