The XB-19 project was intended to test flight characteristics and design techniques for giant bombers.

Despite advances in technology that made the XB-19 obsolete before it was completed, the Army Air Corps believed the prototype would be useful for testing despite Douglas Aircraft wanting to cancel the expensive project.

[a] Its construction took so long that competition for the contracts to build the XB-35 and XB-36 occurred two months before its first flight.

[2][b] In 1943, the Wright R-3350 engines were replaced with liquid-cooled W24 Allison V-3420-11 by the aircraft division of Fisher Body in support of the XB-39 project.

[c] Data from McDonnell Douglas aircraft since 1920: Volume I[13]General characteristics Performance Armament