 In 2012, the gross domestic product (GDP) of the Houston–The Woodlands–Sugar Land metropolitan statistical area (MSA) was $449 billion, the fourth-largest of any metro area in the United States.The Houston metropolitan area comprises the largest concentration of petrochemical manufacturing in the world, including for synthetic rubber, insecticides, and fertilizers.It is the world's leading center for oilfield equipment construction, with the city of Houston home to more than 3,000 energy-related businesses, including many of the top oil and gas exploration and production firms and petroleum pipeline operators.