North Charleston, SC

BOEING came to South Carolina more than seven years ago to establish a second assembly line for its 787 Dreamliner aircraft. At least part of the attraction, analysts said, was the area's lightly unionised labour force - giving the company more leverage over the union at its main operations outside Seattle.

Now that equation is being put to the test. Workers will vote on Wednesday on whether to unionise, an early test of organised labour's strength in the Trump era.