The highway travels from its southern terminus at the Florida state line, southwest of Donalsonville, where the roadway continues as Florida State Road 2 (SR 2), northeast through Albany to its northern terminus, an intersection with SR 32 at a point northeast of the city.

[8][9] By the beginning of August, the southern terminus was truncated to just east of the Florida state line.

[10][11] The next month, the southern terminus was truncated again to just east of the Florida state line.

[12][13] In August 1933, the segment from the SR 62 intersection to Albany had a "completed hard surface".

[16][17] By the beginning of October, a small portion in the southwestern part of Albany was under construction.

[17][18] At the end of the year, the highway was extended north on US 19/SR 3 to the northern part of Albany and then on a sole path to the Dougherty–Lee county line just east of the Chehaw State Park.

[18][19] By September 1938, the Dougherty County portion of the Newton–Albany segment had a completed hard surface.

[19][20] By July 1939, the entire portion of SR 91 in Donalsonville had a completed hard surface.

A small portion just west of the Miller–Baker county line had completed grading, but was not surfaced.

[20][21] By October, the Baker County portion of the Newton–Albany segment had a "sand clay or top soil" surface.

[25][26] By the middle of 1941, nearly the entire segment from the Florida state line to Donalsonville had a sand clay or top soil surface.

[32][33] Between June 1955 and July 1957, SR 32's path between Leesburg and Ashburn was shifted to the northeast.

[36][37] In 1973, the path of SR 91 in the Newton area was shifted southeast to travel through the city.

is a 1.9-mile-long (3.1 km) alternate route of SR 91 that exists almost entirely within the city limits of Donalsonville.

The alternate route begins at an intersection with the SR 91 mainline (Marianna Highway) in the southern part of the city.

It continues to the north, then curves to the north-northeast, and crosses over some railroad tracks of CSX.

It passes the Donalsonville Hospital Emergency Center and then curves back to the north-northeast again until it meets its northern terminus, another intersection with the SR 91 mainline just north of the city limits of Donalsonville.

The concurrency curves again to the southeast and intersects the southern terminus of SR 91 Spur, where the truck routes leave US 27/SR 1.