Chicago has the third largest gross metropolitan product in the United States. The city has also been rated as having the most balanced economy in the United States, due to its high level of diversification. Chicago is a major world financial center, with the second largest central business district in the United States. The city is the headquarters of the Federal Reserve Bank of Chicago (the Seventh District of the Federal Reserve). The city and its surrounding metropolitan area are home to the second largest labor pool in the United States with approximately 4.25 million workers. In addition, the state of Illinois is home to 66 Fortune 1000 companies, including those in Chicago.