BP, then British Petroleum, acquired Chicago-based Amoco in 1998 for $48 billion and it continues to have a large presence in the Chicago area. The firm employs about 1,800 workers in the area, including Naperville, where it operates a research hub. Chicago is the U.S. headquarters of Air BP, a supplier of aviation fuel products, as well as BP's pipeline operations. The city is also a base, along with Houston, for the company's trading activities. BP hasn't broken down details of how the job reduction will affect specific regions or businesses, BP spokesman Paul Erwood said in an emailed statement.