Page 277. " Yes I am, he said. I am the one. "

Despite his evocation of a world seemingly abandoned by God, McCarthy’s stance on religion is never clear. However, he consistently employs the language of religion and a Biblical style.

Page 280. " He walked through the town and down to the docks "

Disused dock
Creative Commons Attribution Share AlikeDisused dock - Credit: David Wright

Page 291. " In the evening, the murky shape of another coastal city "

Exactly which coast the road has led to is unclear, but it is likely to be either the Atlantic coast of Georgia or South Carolina, or the Gulf coast of Florida.

 

Google Map

 

If it's the Gulf coast, then a likely candidate for this "murky shape" is Panama City.

 

Page 293. " Dead trees standing out of the gray water trailing gray and relic hagmoss "

Big Cypress National Preserve, Florida
Creative Commons Attribution Share AlikeBig Cypress National Preserve, Florida - Credit: Ianare Sevi, 2005
This "dead swamp" supports the idea that they are on Florida's Gulf Coast. 

The word "hagmoss" seems to be an invention.  This is probably Spanish-moss (also called graybeard), which is not a true moss but an epiphytic plant.