[2][3] It later moved into a loft on the fifth floor at 351 West 52nd Street in the Hell's Kitchen neighborhood of Manhattan.

[4][5] In 1921, the firm leased a vacant lot at 420-428 East 31st Street in the Kips Bay neighborhood of Manhattan, located on the block between First Avenue and the East River, and built a new factory on the site.

[6] The company built a floating ramp for amphibians alongside the pier at the end of 31st Street—which it leased from the city—that enabled aircraft to taxi in and out of the water.

[7] Before this, aircraft from the factory were brought out to the pier and had to be hoisted into the East River using a crane.

[3] With the planned closure of Loening's factory in New York City and a move of its operations to Keystone's plant in Bristol, Pennsylvania, several of Leoning's employees—including Leroy Grumman, Jake Swirbul and William Schwendler—decided to remain in New York and formed their own company on Long Island, the Grumman Aircraft Engineering Corporation.