After a crossing of Webster Creek, the highway curves to the east-northeast and has an interchange with SR 113 (Carrollton Street).

It briefly leaves the city limits of Lithia Springs and crosses over Sweetwater Creek on the Blair Bridge.

It curves to the east-northeast and finally enters Atlanta proper on the Adamsville–Old Gordon neighborhood line in the western part of the city.

This interchange is just south of the Basoline E. Usher Elementary School and on the southwestern edge of Harwell Heights Park.

Just north of Westview Cemetery, it travels along the southern edge of the Penelope Neighbors neighborhood.

It immediately curves back to the southeast and begins to travel along the southern edge of the Mozley Park neighborhood.

Upon reaching a partial interchange with Langhorn Street SW, which is only accessible from the westbound lanes, it enters the West End neighborhood.

Upon crossing over Lawton Street SW, it begins to briefly travel on the West End–Harris Chiles neighborhood line.

It passes The Mall West End at a partial interchange with Lee Street, which is only accessible from the westbound lanes.

It begins to curve to the east-southeast and has a partial interchange with Columbia Drive, which is only accessible from the eastbound lanes.

The Interstate travels under a bridge carrying Wesley Chapel Road and curves to the southeast.

It then passes Hillandale Memorial Gardens just before an interchange with Evans Mill Road and Lithonia Industrial Boulevard.

After traveling under a bridge that carries SR 81, it very briefly cuts across the extreme southeastern corner of Oxford and then re-enters Covington.

The highway has a crossing of Dennis Creek and then leaves Social Circle and enters Morgan County.

It travels on a bridge over Fourmile Branch and some railroad tracks of Norfolk Southern Railway.

After a crossing of North Sugar Creek, it curves to a southeasterly direction and has an interchange with Seven Island Road.

It crosses over Euchee Creek and Mill Branch before an interchange with SR 388 (Horizon South Parkway/Lewiston Road).

After crossing over Cranes Creek, it travels south of Warren Road Elementary School.

Several stretches of I-20 are named for various people and reasons: I-20's path through Atlanta was designed in the late 1950s, during the era of segregation.

[2] By 1966, the highway was proposed from the Alabama state line to SR 5 in Douglasville, was open from Douglasville to the western part of Atlanta, under construction in the western part of Atlanta, was open from downtown Atlanta to US 278/SR 12 near Social Circle, was under construction from that point to SR 83 in Madison; proposed from Madison to the Warren–McDuffie county line, under construction from there to the South Carolina state line.

[14][15] In 1968, it was open from Douglasville to Madison and from just north of Thomson to the South Carolina state line.

[26][27][28] From a period of late 2014 to mid-2015, GDOT proposed to widen I-20 from the Alabama state line eastward to Villa Rica, GA.

Phase 2 is being prepared to add the additional third lane on I-20 from the Alabama state line to the Villa Rica interchange which is I-20 exit 24.

[29] Outside of the west side of Atlanta, this project calls for improvements of the interchange and addition of lanes along I-20 in Cobb, Douglas, and Fulton counties.

This project focuses on reconstructing the interchange to remove left hand exits and improve design speed, and modification and/or replacement of existing bridges and ramps, construction of an I-20 westbound CD system from the interchange to Fulton Industrial Boulevard (FIB), construction of lanes and improvements along eight miles (13 km) of I-20 in both directions from Thornton Road to Hamilton E. Holmes Drive, modification and/or replacement of bridges along I-20, including bridges over CSX Railroad and the Chattahoochee River and finally, the addition of new lanes and improvements along two miles (3.2 km) of I-285 southbound from Hollowell Parkway to Martin Luther King Jr.

[30] Outside of the east side of Atlanta, this project will improve traffic flow and safety at this busy interchange.

This critical junction in DeKalb County requires operational and geometric improvements to address inefficient flow of traffic and safety performance.

[32][33] From a period of late 2014 to mid-2015, GDOT proposed to widen I-20 from the Alabama state line eastward to Villa Rica.

Phase 2 is being prepared to add the additional third lane on I-20 from the Alabama state line to the Villa Rica interchange (exit 24).

The project will widen 1.8 miles (2.9 km) of I-20, replace four bridges over the Augusta Canal and Savannah River, and make intersection improvements at the West Martintown Road interchange in South Carolina.