It’s probably not where you’re thinking. You’re probably thinking of somewhere east, near Key West, or something just straight south, near Laredo.
South Point on the Big Island of Hawai’i holds the title for being the southern most point in the United States.
And it looks nothing like what you imagine.
Shot on Canon 5dii + 50mm f1.4 | Fuji X-Pro 1 +23mm f2