Tank manufacturing during WWII

M3 General Grant tanks nearing completion at the newly-built Chrysler Tank Arsenal. The Army Ordnance Department always perceived the M3 as an inadequate design, and only relied upon it as a stopgap. The M3’s major defects were the main 75-mm gun was mounted on the right corner of the hull, and had only a fifteen-degree field of fire. The tank was too tall, and the riveted turret and hull, Hyde writes, “weakened its armament and was a serious hazard to the crew and nearby infantry if it suffered a direct artillery hit”. Nonetheless, during 1941 and 1942, the M3 was the best available design for a medium-sized tank that could be produced quickly.

 The next-generation M4 General Sherman tank, in its last stages of assembly at the Chrysler Tank Arsenal in June of 1944. Unlike the M3, the M4’s 75-mm gun, being in a turret, could swivel 360 degrees. In another improvement, the hull was welded, rather than riveted. The pile of jagged-looking rolls in the middle of the photo is a stack of tank treads.

Rebecca Onion has a Slate article about World War Two:

The photos above come from a new book of photographs from Detroit, Michigan’s wartime factories, Images from the Arsenal of Democracy, by historian Charles K. Hyde. The book takes its title from Franklin D. Roosevelt’s 29 December 1940 fireside chat, in which the President called upon Americans to support the new industrial effort to arm American allies: “We must be the great arsenal of democracy. …We must apply ourselves to our task with the same resolution, the same sense of urgency, the same spirit of patriotism and sacrifice, as we would show were we at war.”
The manufacturing of tanks was a particular priority, as the German army had by far outpaced its adversaries in this area. In the late 1930s, Hyde writes: “the Army was not using tanks in any combat capacity and there were no facilities in the United States to manufacture tanks, not even in small quantities.” As late as 1939, the Army Ordnance Department awarded tank contracts to companies that manufactured railroad equipment, before determining that automotive concerns would be far more capable of the level of mass production that was needed.
These images, taken by photographers working for the Automotive Council for War Production, capture some workers who were part of the effort to close the tank gap.

Rico says it's a good thing we did; we'd need them by 1944...