Arkansas US 78 begins at interchange with
I-57/
US 67 at exit 102 where the roadway continues as
AR 226 west toward
Swifton. The route goes through towns of
Cash,
Jonesboro,
Lake City,
Black Oak,
Monette,
Manila and
Blytheville. In Blytheville, the route runs concurrently with
Interstate 55 (I-55) and travels south, going through
Marion and
West Memphis before turning east and crossing on the
Memphis & Arkansas Bridge over the
Mississippi River to enter
Memphis, Tennessee.
Tennessee US 78 enters
Tennessee along I-55 from
Arkansas and shortly after diverges from I-55 onto E.H. Crump Boulevard. It is concurrent with
US 61,
US 64,
US 70,
US 79 and
State Route 1 (SR 1) until Third Street/B.B. King Boulevard. US 61 turns south onto
SR 14 south (Third Street) while US 64, US 70, and US 79 turn north onto
SR 4 west and SR 14 north (B.B. King Boulevard) at this intersection. This is also where SR 4 becomes concurrent with US 78 for the remainder of its length. About a later, SR 1 turns north onto (Danny Thomas Boulevard). US 78/SR 4 then continues along E.H. Crump Boulevard to meet two interchanges with
I-240 (the first interchange of I-240 is concurrent with
I-69). Around I-240, the road changes names to Lamar Avenue and then it meets
US 51 and
SR 3 before continuing southeastwardly to the
Mississippi state line. West of Jasper, old US 78 is signed as SR 118 to Guin, and the segment from Guin northward to I-22 at Hamilton is signed as US 43/US 278.
Georgia US 78 enters Georgia in
Haralson County, passing through the downtowns of
Tallapoosa and
Bremen. It then proceeds through
Carroll County and
Douglas County. In Douglasville, located in Douglas County, US 78 runs through the downtown, historical part of the city. It is the original thoroughfare for these Georgia counties. The route then continues eastward through
Cobb and
Fulton counties into
Atlanta. After crossing
Peachtree Street, where US 78 marks a boundary between
Downtown and
Midtown, US 78 is largely conterminous with
Ponce de Leon Avenue. As it proceeds due east, this section of the route passes
Ponce City Market and crosses the
Eastside Trail of the
BeltLine before skirting a number of
Frederick Law Olmsted-designed parks in the
Druid Hills Historic District at the eastern edge of the city. After entering
Decatur in
DeKalb County, US 78 departs from Ponce de Leon Avenue to head northeast. South of the site of
North DeKalb Mall, another short freeway portion begins — leading from just inside the eastern rim of
Interstate 285 (the Perimeter) to the
suburbs of
Clarkston,
Tucker,
Stone Mountain, and
Snellville. This portion is named the
Stone Mountain Freeway, and provides an excellent view of
Stone Mountain for eastbound motorists. The route then proceeds east across
Gwinnett,
Walton, and
Oconee counties. In Oconee County, US 78 leaves Moina Michael Highway at the
SR 316 interchange, turning right and running concurrently with SR 316/
US 29. (From this point, Moina Michael Highway is signed as
US 78 Business, which follows the original route of US 78 through Athens) At the terminal eastern interchange of SR 316 both US 78 and US 29 turn right and join with
SR 10 Loop, a mostly Interstate-grade bypass that rings
Athens-Clarke County. US 78 exits the bypass and turns right at the Lexington Road interchange. From there US 78 passes through
Oglethorpe,
Wilkes,
McDuffie and
Columbia Counties into
Augusta and then onto one of the twin bridges across the
Savannah River into South Carolina.
South Carolina US 78 provides the most direct route between Augusta and Charleston, through the
South Carolina Lowcountry. Crossing
Savannah River into the state, it goes northeast into
Aiken before going southeasterly through the cities and towns of
Williston,
Blackville,
Denmark,
Bamberg,
Branchville, and
St. George. East of
Dorchester, it parallels
I-26 into downtown Charleston, where it ends. ==History==