The Battle of Alligator Bridge took place around Callahan on June 30, 1778, and was the only major engagement in an unsuccessful campaign to conquer British East Florida during the American Revolutionary War.

According to the United States Census Bureau, the town has a total area of 1.3 square miles (3.4 km2), all land.

The climate in this area is characterized by hot, humid summers and generally mild winters.

As of the 2020 United States census, there were 1,526 people, 565 households, and 396 families residing in the town.

US Routes 1 and 23 run together northbound in an overlap from the Grand Park section of Northwest Jacksonville through the St. Mary's River.

US 301 joins US 1 and 23 from an overlap with hidden State Road 200, that begins as far south as Ocala.

Florida State Road 115 runs from the Deercreek section of Southeast Jacksonville and terminates with US 1 and 23 south of downtown, but contains a de facto extension at the northern edges of town in the form of CR 115 on Kings Road and Old Dixie Highway.

CR 108 is known as North Brandies Avenue then becomes Saint George Road as it loops around western Nassau County then curves to the east while passing through Hillard where it runs through another intersection with US 1, 23 and 301.

The road continues east through northern rural Nassau County briefly passing through Evergreen, and finally terminates at US 17 north of Becker.