The First Airport in the US: College Park Airport

 - From Wikipedia: 

College Park Airport was established in August 1909 by the United States Army Signal Corps to serve as a training location for Wilbur Wright to instruct two military officers to fly in the government's first airplane. Leased on August 25, the first airplane, a Wright Type A biplane, was uncrated and assembled on October 7. Civilian aircraft began flying from College Park Airport as early as December 1911, making it the world's oldest continuously operated airport.[3] In 1977, the airport was added to the National Register of Historic Places.[1][4]

College Park Airport is home to many "firsts" in aviation, and is particularly significant for the well-known aviators and aviation inventors who played a part in this field's long history. In 1909 Wilbur Wright taught Lieutenants Frederic Humphreys and Frank Lahm. Humphreys became the first military pilot to solo in a government airplane. The same year on October 27, Mrs. Ralph Henry Van Deman was flown by Wilbur Wright to become the first woman to fly in a powered aircraft in the United States.

. . . In 1911, the nation's first military aviation school was opened at College Park, with newly trained pilots then-Lt. Henry H. Arnold and Lt. Thomas DeWitt Milling as Wright pilot instructors and Capt. Paul W. Beck as the Curtiss instructor. William Starling Burgess also brought a licensed Wright Model B named the Burgess Model F.[8] The military aviation school saw numerous aviation firsts. Shortly following the cancellation of an international air meet at the airport in the fall of 1912, all aviators on the field participated in a demonstration for the International Congress of Hygiene participants.

. . . In 1918, after a three-month trial with the War Department beginning May 15, the Post Office Department inaugurated the first Postal Airmail Service from College Park, serving Philadelphia and New York City (Belmont Park). Flights from College Park continued until 1921. The compass rose and original airmail hangar remain at the modern airport as a witness to this history. The airport code "CGS" originally referred to the airport's purpose in the 1930s as an airmail station (CGS = ColleGe Station).

In 1920, Emile and Henry Berliner (father and son) brought their theories of vertical flight to the field and in 1924 made the first controlled helicopter flight.

From 1927 until 1933, the Bureau of Standards developed and tested the first radio navigational aids for use in "blind" or bad weather flying. This was the forerunner of the modern Instrument Landing System used today by aircraft.

In 1937 the Engineering & Research Corporation (ERCO), based across the street (Good Luck Rd, now Campus Drive) in nearby Riverdale, Maryland, used the airport to test fly the early model of the Ercoupe, an airplane designed to be spin-proof.