LaGuardia Airport opened in 1939. It is located at the northern part of the New York City borough of Queens. The combination of JFK International, LaGuardia, and Newark Liberty International airport creates the largest airport system in the United State and the largest total flight operations in the world. The airport is a hub for Delta Air Lines and American Airlines. Nonetheless, LaGuardia has been criticized for some of its obsolete facilities and ranked as the worst in the United States on various customer surveys. The airport was originally Glenn H. Curtiss Airport and it was renamed North Beach Airport later. After New York City managed and redesigned the airport, it was called New York Municipal Airport-LaGuardia Field, and the in 1953 named "LaGuardia Airport" after the mayor of New York, Fiorello La Guardia at the time. The current location was originally owned by the Steinway family and used as private flying field. Later it was developed into the commercial airport initially supported by Fiorello La Guardia. Construction of a new airport began in Queens to take advantage of convenient accessibility to Manhattan through the newly built Queens-Midtown Tunnel. The airport opened on December 2, 1939 as the New York Municipal Airport. After the completion of construction, the public was fascinated by the idea of air travel and visited the airport, paying the dime fee to watch the airliners' landing and taking off. Within two years, income derived from parking and non-travel reached $935,000 a year and the airport became a huge financial success. The airport was used as a training facility for aviation technicians and as a logistics field during World War II. After the Port Authority of New York and New Jersey took over the control in 1947, the modern name was created and it instituted various innovations and improvements. Increasing traffic and safety issues at LGA elicited extra fees during peak hours. Also, the Port Authority began a Sunday-thru-Friday "perimeter rule", restricting nonstop flights from LaGuardia to cities more than 1,500 miles away to alleviate the traffic. The September 11, 2001 terrorist attacks on New York City further diminished the traffic. The main facilities consist of four terminals: Terminal A, B, C, and D. Terminal A was the original airport terminal building serving international travels during 1940s. Terminal B is known as Central Terminal Building and was dedicated on April 17, 1964. It serves mainly domestic flights. Terminal C launched in September 1992, was designed for a food, retail, and concessions court and a Welcome Center for the arrivals. Terminal D was built by Delta Air Line and opened in June 1983. The city of New York invested $40 million and the Port Authority spent $1.4 billion to construct and develop the airport. About 11,000 employees work there and the airport contributes more than $15.6 billion in economic activity to the New York-New Jersey metropolitan region, leading to about 116,000 jobs and $5.7 billion annual salaries in the region.