The Douglas XB-19 was the largest bomber aircraft built for the United States Army Air Forces until 1946. It was originally given the designation XBLR-2 (XBLR- denoting Experimental Bomber, Long Range).
The XB-19 project was intended to test flight characteristics and design techniques for giant bombers; Douglas Aircraft wanted to cancel the expensive project. Despite advances in technology that made the XB-19 obsolete before it was completed, the Army Air Corps felt that the prototype would be useful for testing. Its construction took so long that competition for the contracts to make the XB-35 and XB-36 occurred two months before its first flight.
The plane flew on 27 June 1941, more than three years after the construction contract was awarded. In 1943 the Wright R-3350 engines were replaced with Allison V-3420-11 V engines. After completion of testing the XB-19 served as a cargo carrier until scrapped at Tucson in 1949.