Interstate 65' - enters the area at the southern Morgan County line between Morgan and Cullman Counties, near Lacon. Bends around a mountain where it passes over US 31. It continues north towards Hartselle where it enters the city limits for about 3 miles. Leaving Hartselle, I-65 travels towards Decatur where small portions of the city limits leak over into rural Priceville. I-65 soon is lifted onto a bridge, linking Morgan County and Limestone County. After entering Limestone County, an interchange with I-565, Alt US 72, and Alabama 20 give routes to Huntsville, and Decatur.
U.S. Highway 31' - from the southern Morgan County line between Morgan and Cullman Counties, near Lacon. The route continues north, passing under I-65, towards Hartselle. After traversing through Hartselle, US 31 briefly enters unincorporated land, but quickly enters the Decatur city limits. As the highway passes through Decatur, it gives access to places such as: Decatur High School / Ogle Stadium, Cooks Natural Science Museum, and views of the downtown area. US 31 leaves the metro area after passing over the Captain William J. Hudson "Steamboat Bill" Memorial Bridges into Limestone County where the Decatur city limits end.
* U.S. Highway 72 Alternate' - enters the metro area in the Limestone County portion of Decatur at the interchange with I-65 and I-565.. Crosses the Tennessee River on the Captain William J. Hudson "Steamboat Bill" Memorial Bridges, combined with US 31 and State Route 20, into urban northern Decatur. Alt 72 bends west and continues into the industrial portion of Decatur. The Port of Decatur, and such notable industries as The United Launch Alliance, Solutia, Vulcan Materials, and 3M have operations along this route. The United Launch Alliance is especially important, since all satellite launch vehicles used by NASA, are produced at this single location. Alt 72 eventually leaves the metro area as it exits Lawrence County, and enters Colbert County of The Shoals.
U.S. Highway 231' - enters the metro area from southern Huntsville. Crossing the Tennessee River, connecting Madison and northeastern Morgan Counties. US 231 continues south, passing through Morgan City, towards the Gadsden area.
State Route 20' - enters the metro area in the Limestone County portion of Decatur at the interchange with I-65 and I-565.. Crosses the Tennessee River on the Captain William J. Hudson "Steamboat Bill" Memorial Bridges, combined with US 31 and U.S. Highway 72 Alternate, into urban northern Decatur. Alabama 20 bends west and continues into the industrial portion of Decatur. The Port of Decatur, and such notable industries as The United Launch Alliance, Solutia, Vulcan Materials, and 3M have operations along this route. The United Launch Alliance is especially important, since all satellite launch vehicles used by NASA, are produced at this single location. Alabama 20 eventually leaves the metro area as it exits Lawrence County, and enters Colbert County of The Shoals.
State Route 24
State Route 33
State Route 36
State Route 67' - enters the area at Hulaco and continues to Somerville. Passes by the old Morgan County Courthouse. Travels through Priceville, and enters Decatur at an interchange with I-65. As SR 67 crosses 6th Avenue it becomes known as the Beltline, a bypass that was constructed to alleviate traffic problems on the swollen 6th Avenue. The highway continues on a north-northwesterly curve and terminates at US 72 Alt./SR 20 inside Decatur.
