Comment by palefirewax

When I was working at Boeing, my boss who was around during those times gave this anecdote.

Apparently in return for being allowed to build the 777, the city of Everett (maybe it was Renton or the state of Washington) demanded large amounts of public works/benefits. Boeing was not pleased with this but in order to make the 777 happen they did all the stuff required. However, they vowed to never have to deal with such nonsense again. To make that happen, they moved their HQ (it was eventually decided to be Chicago) and began to consider relocating their plants to another state. Eventually, that became South Carolina. Or so the anecdote goes.

I don't think my boss was very high up back then, so I can't speak to how factual it is, but it sounds plausible.