In 1937, Imperial Airways and Pan American World Airways began operating scheduled flying-boat airline services from New York and Baltimore to Darrell's Island, Bermuda. In 1948, regularly scheduled commercial airline service by land-based aeroplanes began to Kindley Field (now L.F. Wade International Airport), helping tourism to reach its peak in the 1960s–1970s. By the end of the 1970s, <answer>international business</answer> had supplanted tourism as the dominant sector of Bermuda's economy (see Economy of Bermuda).
What became the main source of Bermuda's economy in the 1970's?
international business