Interstate 24 (I-24) runs for just over 317 miles through parts of the Midwest and Southeast. It begins at its junction with I-57, 10 miles south of Marion, Illinois. It then runs through parts of Kentucky, Tennessee, Georgia and then ends back in Tennessee at its junction with I-75 in Chattanooga.
Like other even-numbered interstates in the United States, I-24 is signed as a west-east route, although its actual route follows a more northwest to southeast routing. I-24 is designated a high-traffic corridor between St. Louis and Atlanta. In addition to I-24, this corridor also includes I-57 and I-64 northwest of I-24, and I-75 southeast of I-24.
I-24 in Illinois
In Illinois, I-24 begins at I-57’s exit 44, in southern Williamson County. The county is in southern Illinois, in an area known as “Little Egypt. The highway heads southeast, passing through several rural counties and passing a number of small towns such as Goreville, Tunnel Hill, Vienna, Big Bay, New Columbia, Round Knob and Metropolis. East of Metropolis I-24 crosses over the Ohio River into Kentucky on the Interstate 24 Bridge. Within Illinois, I-24’s length is 38.73 miles.
I-24 in Kentucky
Once in Kentucky, Interstate 24 runs for 93.37 in the state. First, it passes to the west of Paducah, near where it intersects US Routes 45, 60 and 62. East of Paducah, I-24 merges with I-69 and the two interstates run concurrently. The two interstates cross the Tennessee River and then cross the Cumberland River. The joined interstates were built along the north shore of the Cumberland River. Just north of Mineral Mound State Park I-69 splits off to the east. At that point I-24 continues east, heading away from the river and runs through farmland for several miles. The highway passes south of Hopkinsville and there is an interchange with I-169. As I-24 nears the Kentucky-Tennessee border, it passes north of Fort Campbell before crossing into Tennessee.
At 180.16 miles, the length of Interstate 24 in Tennessee is more than its length in the other three states combined. Also, there are two separate segments of I-24 in Tennessee, which are separated by the segment in Georgia.
Entering Tennessee from Kentucky, I-24 passes near Clarksville and then crosses the Red River. Although the highway has a long straightaway at that point, it also has several steep grades. Passing Springfield, I-24 passes through the rolling, hilly terrain of the Nashville Basin.
There are several miles of rural woodlands and steep grades prior to I-24’s interchange with SR 45, which signals the highway’s approach to the metropolitan Nashville area. I-24 soon widens and there is an interchange with SR 155, the northern beltway around Nashville. In less than a mile, I-24 and I-65 merge, widening again and running southward. I-65 splits off before I-24 enters downtown Nashville. After several interchanges I-24 crosses the Cumberland River via the Silliman Evans Bridge, and merges with Interstate 40. The combined interstates run southeast for a few miles and then I-40 splits off to the east toward Knoxville. I-24 continues in a southeastern direction, interchanging with US routes, I-440 and the southern side of SR 155. The highway continues on a southeastern course, traveling through suburban Nashville for several miles. It crosses into Rutherford County near LaVergne. From that point, I-24 follows a mostly straight and flat route through middle Tennessee.
There is an interchange with I-840, which is the outer southern beltway around Nashville. Shortly thereafter I-24 enters Murfreesboro, Nashville’s largest suburb. After leaving Murfreesboro, I-24 narrows as it enters a more rural area. On this section, the highway runs relatively straight for a number of miles.
After an interchange with SR 64, I-24 curves south, then east. The highway passes through Manchester and then continues through a rural area for several miles.
After a relatively easy trip through much of Tennessee, motorists traveling east on I-24 encounter a hazardous segment approximately 40 miles west of Chattanooga. Near Monteagle, I-24 crosses the Cumberland Plateau. This stretch of highway can be quite difficult for trucks, particularly when they are heading east toward Chattanooga. The eastbound grade has a protracted 4%-6% grade over several miles. While there are steeper grades in Tennessee (on I-40 and I-24 north of Nashville), this stretch is dangerous nonetheless. The highway has three lanes in each direction on this stretch of roadway; there are also two runaway truck ramps. However, because of the area’s topography, the two ramps are located on the left side of the grade. While crossing the Cumberland Plateau, the speed limits are reduced; however, that is not an effective deterrent for some motorists (in cars and trucks).
The eastern Monteagle grade also is known for its wide medians. Along one section of the highway there is more than a mile between the eastbound and westbound lanes. This is because the eastbound lanes descend on one side of Monteagle Mountain using the roadbed of the original three-lane highway (US 41/US 64). That road had two ascending lanes and one descending lane before the interstate was built. The westbound lanes of I-24 in this area ascend the other side of the mountain on a new roadbed.
After leaving Monteagle Mountain, the highway runs for several miles through a flat gorge with long straightaways and few curves. Several miles further, the eastbound and westbound lanes split, with a median more than one-half mile apart. In this case the width of the median is not because of topography but because of right-of-way acquisition disputes. I-24 travels over a large hill and then crosses Nickajack Lake before entering a narrow area of the gorge. The highway enters the Eastern Time Zone and is in Hamilton County for less than one-quarter of a mile before entering Georgia.
I-24 travels along the southern flank of Georgia’s Raccoon Mountain for 4.10 miles (its total length in the state). About 1.5 miles after entering Georgia there is an interchange with I-59. I-24 then turns north and re-enters Tennessee.
Tennessee (Part 2)
I-24 re-enters Tennessee’s Hamilton County, running through Lookout Valley for several miles. A few miles later, I-24 curves sharply eastward and runs on a narrow causeway between the Tennessee River and the northern tip of Lookout Mountain. After another mile, the highway curves sharply north. As it enters Chattanooga, there is a three-way interchange with US 27, which is a freeway at that point. The two highways run together, curving first sharply to the east, and then to the west about one mile later. At that point US 27 splits off to the south. There are a number of interchanges with major city streets, and then I-24 reaches the “Ridge Cut,” a section of Missionary Ridge between the 4th Avenue exit and the Germantown/Belvoir exit. The interstate curves sharply northward, then eastward, crossing the ridge with an extremely steep grade. Unfortunately, this is a major bottleneck; accidents and congestion are common. At the top of the Ridge Cut, I-24 runs along a relatively flat and straight section, with interchanges with several Chattanooga streets. About three miles later at East Ridge, I-24 reaches its eastern terminus at I-75.
The original Interstate Highway System (IHS) plan introduced in 1956 included I-24 between Nashville and Chattanooga. Construction on two of I-24’s first sections (both in Tennessee), began in 1958. These were the section between downtown Nashville and Rutherford County, as well as the interstate’s eastern terminus with I-75.
As was the case with other interstates around the United States, construction of I-24 began and was completed in stages.
Illinois authorized engineering for its segment of I-24 in 1966 and authorized construction in 1968. Illinois’ final segment of I-24 opened to traffic in late January 1976. That segment cost $32.5 million then (the equivalent of $116 million in 2021).
Only a small section of I-24 was being built in Kentucky before 1970. In the original plan for the IHS, I-24 was only laid out between Nashville and Chattanooga. The extension northwest through Kentucky to Illinois was included with additions approved in October 1957. Therefore, I-24 was first planned through western Kentucky in 1958.
Kentucky began construction on its segments of I-24 in December 1967 in Lyon County. The Ohio River Bridge cost $18.6 million to build ($76.5 million today). It opened in October 1974.
The final section of I-24 to be completed was a 23-mile section from the Western Kentucky Parkway to U.S. 68 east of Cadiz. It opened to traffic on May 23, 1980.
The Georgia Department of Transportation opened I-24 between its interchange with I-59 and the Tennessee border (as well as the eight northernmost miles of I-59) on September 10, 1968.
In Chattanooga, the interstate was completed through the central part of the city in 1963, and the remainder of the city in 1965. The section along the Ridge Cut was dedicated on December 1, 1965. The section between US 27 west of Chattanooga and the Georgia state line was finished on December 16, 1966. In Nashville, the segment between the I-40 split and the I-65 split was dedicated on January 14, 1964. The section of I-24 from Marion County to Monteagle Mountain was completed in 1966 and the section between US 41 in Manchester and US 64 near Pelham on July 27, 1967. The Nickajack Lake bridge was opened to traffic on December 18, 1967. The construction over Monteagle Mountain took several years (1962-68).
On December 9, 1970, the section of I-24 between US 231 in Murfreesboro and SR 64 was opened. That was followed by the section between SR 171 in Nashville and US 231 in Murfreesboro on December 31, 1970. The final segment of I-24 between Nashville and Chattanooga, which was between SR 64 and US 41 northwest of Manchester, was opened and dedicated on December 16, 1971. Work on I-24 from the Kentucky line through Clarksville began in 1970; construction of I-24 between Clarksville and Nashville was underway by 1972, and was finished in early 1975. This 44-mile segment was among the last segments of I-24 completed in Tennessee; and it was difficult because of the rugged and hilly terrain.
The 32-mile segment of I-24 between Hopkinsville, Kentucky and Clarksville, Tennessee was opened to traffic by both states on September 12, 1975. The 15-mile section between U.S. 79 and SR 49 in Robertson County opened in September 1976. The last segment of I-24 to be finished in Tennessee was between SR 49 and Interstate 65 in Nashville. It opened to traffic on January 7, 1978; it was more than two years behind schedule at that point.
Like most interstate highways, construction and reconstruction has taken place since I-24 was completed. There are two major renovations highlighted below.
Ohio River Bridge
In 1979, some five years after it was opened to traffic, structural problems were found on the Ohio River Bridge. Among the issues were 119 cracks blamed on defective welding of the tie girders. The tied-arch bridge was closed on August 3, 1979. It remained closed to all automobile traffic through October 1980 and all truck traffic until the summer of 1981.
I-75/24 interchange modification
For years, there was a major bottleneck where I-75 intersected I-24 just north of the Georgia-Tennessee border. In late 2018, the Tennessee Department of Transportation (TDOT) awarded a $132.64 million contract for the design-build project to upgrade the interchange that joined the east end of I-24 with I-75. Work began in the fall of 2019 and was completed earlier this year.
Among the sub-projects in the reconstruction, the ramps to and from I-24 to I-75 were relocated and all other ramps at the interchange were expanded.