Running within a mile of I-95 along most of its length, GA 303 extends southwest to northeast, forming a loop and shorcut for U.S. 17 northwest of Brunswick in Glynn County. GA 303 also serves as an alternate crossing over the Intercoastal Waterway in lieu of I-95 and U.S. 17 over the Sidney Lanier Bridge, which was especially useful prior to the replacement of the old draw bridge on U.S. 17. However, the 9-mile highway still greatly diminished in importance when I-95 opened in 1977.

GA 303 was originally commissioned in 1957 along what had been U.S. 17. The previous year, U.S. 17 was moved to the then new Sidney Lanier Bridge with the state overlap, GA 25, breifly retained on the old route prior to recommissioning as GA 303. The relocation of U.S. 17 brought the major coastal highway into Brunswick instead of by-passing it to the northwest, but the 6.6 mile old alignment was still a shorter route and still was important enough to remain a state highway.

Compare the two maps. The first is in 1952 prior to the construction of the Sidney Lanier Bridge with U.S. 17 following what is today GA 303. Note the dip south along U.S. 25 (shown here as GA 27) before turning back north on U.S. 17. The second map from 1959 is after the completion of the bridge with the old route retained as GA 303, which was designated GA 25 briefly after the bridge opened.

The original GA 303 ended at U.S. 25/341 and did not extend east of there for many years. At the time it was U.S. 17, no highway directly linked U.S. 17 north, which still forced traffic south along U.S. 25 down to the city itself before turning north again. By 1962, this connection was finally made, but not without a complicated switch to the road that included a sharp intersection with U.S. 25/341, an overlap with the same highway a short ways south then turning back north again at a sharp angle. This extension included three roads: Old Jesup Road, Scranton Road and Chapel Crossing Road. Of these, only Old Jesup Road was paved originally, the other two were not paved until 1965. This extension brought the mileage 2.3 miles longer to 8.9 miles.

Compare the older maps to these later maps, then compare these two. The first is in 1984, a few years after I-95 was completed in the area. Note the extremely close proximity of I-95, the extension of GA 303 and the addition of GA 25 Spur. Cypress Mill Road is shown as a gray line in the first map. The second map is from 1997 shortly after GA 303 was relocated to Cypress Mill Road.

In 1995, the eastern portion of GA 303 was relocated in the 1980's to its shorter present alignment. This new route was created by the construction of a new connector and railroad grade separation from west of U.S. 25/341 to Cypress Mill Road. The former route was problematic, because it had three seperate turns at intersections and many curves that made it a less ideal route for a highway. However, the old route was shorter because it joins U.S. 17 nearly three miles north of its present terminus at U.S. 17. The 1995 relocation was also the last significant change to the highway.