Oklahoma is one of the major oil-producing States in the Country, with an annual production typically accounting for more than 3% of total U.S. production in recent years. Crude oil wells and pipeline systems are concentrated in Central Oklahoma, although drilling activity takes place in the panhandle. One of the is one of the 100 largest oil fields in the United States is found in Oklahoma. The city of Cushing, in Central Oklahoma, is a major Crude oil trading hub that connects Gulf Coast producers to Midwest refining markets.