In the spirit of the approaching 75th anniversary of D-Day, the resources brought to bear in conjunction with WWII were and still are amazing.

This video of B-24 production at Willow Run is fascinating.

https://youtu.be/p2zukteYbGQ

My dad was a B 24 pilot in South China. He was with the Flying Tigers.

1,225,000 parts made up the B-24
Ford produced one plane every hour. That's insane.

It would be hard to believe that you could build that plant in 4 years, much less build it and manufacture 8000+ B-24s. Incredible. 5 plants built:

I was fortunate enough to park my plane in the remaining hangar recently. The amount of history was awe inspiring for sure.

The P-51 prototype was a 100 day wonder with an airframe being completed in a little over 100 days from when the British signed an intent contract.
The engine was delayed a bit and it flew about a month later.
Just prior to the US entry in WWII the Gov built a factory near Dallas TX in Grand Praire for North American Aviation. It also took a touch over 100 days from ground breaking to production starting.
That factory in TX is the reason the T-6/SNJ series are called Texan. All production of the T-6 series was moved there from Mines Field NAA plant, today known as LAX.
The freed up engineering and production space for the P-51 just starting out and the B-25.
Amazing how we could create things quickly when that was a priority.