SWANSBORO, N.C. (AP) — Historic cities and towns along the Southeastern U.S. coast have survived wars, hurricanes, disease outbreaks and other calamities, but now that sea levels are creeping up with no sign of stopping, they face a more existential crisis.

With a total annual budget of $225 million, Charleston, South Carolina, can't afford the billions of dollars to save itself without federal help. It's counting on the U.S. Army Corps of Engineers to help surround its downtown peninsula with seawalls, harkening to the barriers the city built when it was founded 350 years ago.

Keeping water o...