Holding company, Nicor, operates through two principal subsidiaries, Nicor Gas and Tropical Shipping. Nicor Gas is the corporation's largest subsidiary. Founded in 1954 as Northern Illinois Gas, it now serves 2m customers and is one of the largest natural gas distribution companies in the United States. Tropical Shipping is a containerised shipping business, serving the Bahamas and the Caribbean. Nicor also owns several energy-related businesses, including Nicor Services and Nicor Solutions, catering for the retail markets, and Nicor Enerchange, a wholesale natural gas marketing company.