Pool Openings in Roosevelt Field, NY.

The Hempstead Plains Aerodrome originally encompassed 900 to 1,000 acres (405 ha) east of and abutting Clinton Road, south of and adjacent to Old Country Road, and west of Merrick Avenue. A bluff 15 feet in elevation divided the plain into two large fields. The U.S. Army Signal Corps established the Signal Corps Aviation Station, Mineola, on the west field in July 1916, as a pilot training school for members of the National Guard.

When the U.S. entered the war in April 1917, the entire field was taken over and renamed Hazelhurst Field after Leighton Wilson Hazelhurst Jr. Hazelhurst was a native of Georgia and was a graduate of the United States Military Academy. He reported for aeronautical duty at the Signal Corps Aviation School, Augusta, Georgia, on 2 March 1912. On 11 June 1912, while making a flight at College Park, Maryland, as a passenger in an airplane undergoing acceptance tests, the plane crashed to the ground and both the pilot and Lt. Hazelhurst were killed.

An adjacent tract of land south of the Hempstead branch line of the Long Island Rail Road was acquired for expansion, becoming Camp Mills along Clinton Road and Hazelhurst Aviation Field No. 2 to the east, part of the massive Air Service Aviation Concentration Center. Hazelhurst Field No. 2 was renamed Mitchel Field on July 16, 1918, to commemorate John Purroy Mitchel, the former mayor of New York killed in a flying accident on July 6, 1918, while training with the U.S. Air Service in Louisiana. On September 24, 1918, the Army dedicated the eastern portion of Hazelhurst Field No. 1 as Roosevelt Field.