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Total length: 2,552 miles (4,107 km)
Western terminus: Barstow, CA, at JCT I-15
Eastern terminus: Wilmington, NC, at JCT NC 132
States traversed & length in each:
- California — 154 miles (248 km)
- Arizona — 359 miles (578 km)
- New Mexico — 373 miles (600 km)
- Texas — 177 miles (285 km)
- Oklahoma — 330 miles (531 km)
- Arkansas — 284 miles (457 km)
- Tennessee — 455 miles (732 km)
- North Carolina — 420 miles (676 km)
Major cities along route:
- Barstow, CA
- Needles, CA
- Kingman, AZ
- Flagstaff, AZ
- Holbrook, AZ
- Albuquerque, NM
- Santa Rosa, NM
- Amarillo, TX
- Oklahoma City, OK
- Fort Smith, AR
- Conway, AR
- Little Rock, AR
- Memphis, TN
- Jackson, TN
- Nashville, TN
- Knoxville, TN
- Asheville, NC
- Hickory, NC
- Winston-Salem, NC
- Greensboro, NC
- Durham/Chapel Hill, NC
- Raleigh, NC
- Wilmington, NC
Junctions with non-related Interstates:
- Interstate 15: Western terminus in Barstow, CA
- Interstate 17: Exit 195 in Flagstaff, AZ
- Interstate 25: Exits 159B/C in Albuquerque, NM
- Interstate 27: Exit 70 in Amarillo, TX
- Interstate 44: Exit 147 in Oklahoma City, OK
- Interstate 35: Multiplex from MP 151 to MP 153 in Oklahoma City, OK
- Interstate 235: Exit 151C in Oklahoma City, OK
- Interstate 430: Exit 147 in North Little Rock, AR
- Interstate 30: Exit 153B in North Little Rock, AR
- Interstate 55: Multiplex from Exit 277 to Exit 279B in West Memphis, AR
- Interstate 65: Multiplex from Exit 208 to Exit 210A in Nashville, TN
- Interstate 24: Multiplex from Exit 211 to Exit 213 in Nashville, TN
- Interstate 75: Multiplex from Exit 368 (Pine Top, TN) to Exit 385 (West Knoxville, TN)
- Interstate 275: Exit 387A in Knoxville, TN
- Interstate 81: Exit 421 in Dandridge, TN
- Interstate 26: Exit 46A in Asheville, NC
- Interstate 77: Exit 152 in Statesville, NC
- Interstate 85: Multiplex from MP 227 (Greensboro, NC) to MP 259 (Hillsborough, NC)
- Interstate 95: Exit 328 in Benson, NC
Related loops and spurs:
- Interstate 240 — 17 miles long; spur from I-40 southeast of Oklahoma City toward airport; west end and zero-mile point at Interstate 44, east end at I-40; I-40 Exit 165
- Interstate 540 — 86 miles long; spur that goes south around Fort Smith, AR, and north to Bentonville, AR, both “spearing” and multiplexing with I-40; southern independent segment (15 miles long) near Fort Smith was built first, and is numbered with its zero point at I-40 Exit 7, with its terminus at the Oklahoma state line; then I-540 is multiplexed along I-40 for five miles; northern independent segment, which includes the 0.7-mile long Bobby Hopper Tunnel, was completed in the 1990s to relieve the parallel U.S. Highway 71; northern segment is numbered using the Oklahoma state line as its zero point, meaning it breaks off I-40 at its own milepost 20; northern segment leaves I-40 at I-40 Exit 12
- Interstate 440 — 11 miles long; spur that forms a ¼ beltway of Little Rock, AR (SE quadrant); numbered in reverse (zero point south of Little Rock at junction with Interstate 30 and Interstate 530, highest numbering at I-40); very useful bypass of Little Rock for Texarkana-Memphis traffic; I-40 Exit 159
- Interstate 240 — 19 miles long; planned as a full beltway around midtown Memphis, TN, but with the cancellation of an I-40 alignment straight through the midtown area, it became the southern half of said beltway (I-40 itself now occupies the north half); exit and mile numbering starts at 12 rather than 0, reflecting this original planned zero point just east of downtown Memphis; begins at I-40 Exit 12B on the far east side of Memphis, then proceeds south, then west as far as Interstate 55, then back north to I-40 Exit 1E at the so-called “Midtown Interchange”
- Interstate 440 — 8 miles long; essentially a 180° loop south of I-40 bypassing downtown Nashville, TN; doesn’t actually re-connect to I-40 at its eastern end, but I-440 traffic can use a very short stretch of Interstate 24 to return to I-40; named the “Four-Forty Parkway”; I-40 Exit 206
- Interstate 140 — 11 miles long; spur from I-40/75 west of Knoxville, TN, to U.S. Route 129 north of Maryville, TN; named the Pellissippi Parkway over its entire length; I-40/75 Exit 376
- Interstate 640 — 11 miles long; 180° loop, north of I-40, bypassing downtown Knoxville, TN; westernmost 3½ miles multiplexed with Interstate 75; termini at I-40 Exits 385 & 393
- Interstate 240 — 10 miles long; 180° loop, north of I-40, through downtown Asheville, NC; westernmost 4 miles will eventually be multiplexed with Interstate 26 when that highway is finished in North Carolina; termini at I-40 Exits 46 and 53B
- Interstate 540 — 17 miles long; currently a spur passing to the north of Raleigh, NC, ending at U.S. Route 1; planned to eventually become a full outer loop around Raleigh; I-40 Exit 283
- Interstate 440 — 16 miles long; functionally a 180° loop, north of I-40, around three sides (west, north, east) of Raleigh, NC; formerly, but no longer, multiplexed with I-40 around the south side to complete a 25-mile loop; termini at I-40 Exits 293 and 301
- Interstate 140 — 6 miles long; currently a spur from I-40 northeast of Wilmington, NC, to U.S. Route 421 north of the city; planned to become an “outer loop” of Wilmington that will “spear” I-40; I-40 Exit 416
Length I’ve traveled: From western terminus to NC Exit 328 (I-95)
Pacific — Western terminus to California/Arizona border
Mountain — California/Arizona border to New Mexico/Texas border
Central — New Mexico/Texas border to Cumberland/Roane county line, TN
Eastern — Cumberland/Roane county line, TN to eastern terminus
NOTE: Arizona outside of Navajo Nation does not observe Daylight Saving Time. Interstate 40 in Arizona west of milepost 314, and again from milepost 321 to milepost 340, is on Mountain Standard Time (UTC–7:00) year round. From milepost 314 to milepost 321, and again from milepost 340 to the New Mexico state line, I-40 is in Navajo Nation, which observes Mountain Daylight Time (UTC–6:00) during the appropriate parts of the year.
California — San Bernardino
Arizona — Mohave, Yavapai, Coconino, Navajo, Apache
New Mexico — McKinley, Cibola, Bernalillo, Santa Fe, Torrance, Guadalupe, Quay
Texas — Deaf Smith, Oldham, Potter, Carson, Gray, Donley, (re-enters Gray), (re-enters Donley), (re-enters Gray), Wheeler
Oklahoma — Beckham, Washita, Custer, Caddo, Canadian, Oklahoma, Pottawatomie, Seminole, Okfuskee, Okmulgee, McIntosh, Muskogee, Sequoyah
Arkansas — Crawford, Franklin, Johnson, Pope, Conway, Faulkner, Pulaski, Lonoke, Prairie, Monroe, St. Francis, Crittenden
Tennessee — Shelby, Fayette, Haywood, Madison, Henderson, (westbound lanes enter Carroll and then re-enter Henderson), Carroll, Decatur, Benton, Humphreys, Hickman, (re-enters Humphreys), (re-enters Hickman), (re-enters Humphreys), (re-enters Hickman), Dickson, Williamson, Cheatham, Davidson, Wilson, Smith, Putnam, Cumberland, Roane, Loudon, Knox, Sevier, Jefferson, Cocke
North Carolina — Haywood, Buncombe, McDowell, Burke, Catawba, Iredell, Davie, Forsyth, Guilford, Alamance, Orange, Durham, Wake, Johnston, Sampson, Duplin, Pender, New Hanover
A quick hypertext drive: Interstate 40 is one of only four Interstates that stretch the entire length of the North American continent, and it is the third-longest Interstate overall, surpassed only by Interstates 80 and 90. It begins at a directional partial interchange with Interstate 15 in Barstow, CA, and very quickly heads into the vast nothingness of the semi-desert. Between Ludlow and Needles, I-40 climbs and descends a few low (less than 4,500 ft./1,372 m) mountain summits, but for the most part, the highway just crosses the High Desert area. Perhaps 20 miles west of the Colorado River crossing, I-40 descends a long but not very steep grade into the river valley.
For some reason, I-40 dips to the south passing Needles and crosses the Colorado River well south of the path it followed across California; this was probably done to avoid passing the highway through a national park on the Arizona side. About 15 miles into Arizona, I-40 turns to the north to head for Kingman; just before Kingman, the highway climbs a short but fairly steep (about 5%) grade.
The next 25 miles or so east of Kingman are fairly flat, but around milepost 80, I-40 enters the mountains of north-central Arizona. The “ELEVATION 5000” and “ELEVATION 6000” signs that seem to pepper the roadside for the next 65 miles or so are a testament to the mountainous nature of the area. The highway then flattens out a bit to pass through Ash Fork and Williams, then begins climbing a bit more, eventually reaching its highest point (7,330 ft./2,234 m) at the Arizona Divide just west of Flagstaff. Above perhaps 5,500 ft. (1,676 m), the semi-desert vegetation gives way to pine trees and more alpine types of vegetation.
There is one long descent back into semi-desert perhaps 15 miles east of Flagstaff, but for the most part, I-40 stays fairly close to the 6,000-ft. (1,829 m) level for most of the rest of eastern Arizona. Winslow and Holbrook are about the only towns with traveler services until one reaches Gallup, NM, about 20 miles over the state line. For perhaps the first 100 miles in New Mexico, I-40 is fairly flat with only an occasional climb or descent; even the climb to the Continental Divide, near milepost 47 at 7,275 ft. (2,217 m), is very gradual.
There are a few Indian casinos located just off Exits 102 and 108 that always seem to offer better drawing-type giveaways than any casino you’ll find in Vegas: they always seem to be giving away huge amounts of cash, cars, or, for the truckers who stop in, even brand-new Peterbilt tractors. I-40 passes through this reservation for about 40 miles or so. Maybe 25 miles west of Albuquerque, I-40 climbs a long hill going east — this hill is long and steep enough, yet so straight (no curves), that one can have a lot of high-speed fun letting one’s vehicle roll down the hill going west. (There is a 65-mph (105 km/h) minimum speed in the left lane going down this hill westbound.) Around mile 150 or so, looking to the east, I-40 affords an excellent view of Albuquerque and the entire Rio Grande valley.
After descending a long hill into Albuquerque and passing through the city, I-40 begins climbing back into the mountains just east of town. This four-lane section, immediately east of six- and eight-lane segments in Albuquerque proper, is quite heavily traveled and could probably use widening. Eventually, near the tourist-trap town of Moriarty, I-40 comes back down another long hill and settles into the semi-arid ranch land that occupies so much of the western Plains. Over the next 250 miles to Amarillo, TX, not much breaks the monotony of rural eastern New Mexico; Santa Rosa and Tucumcari provide traveler services, and there is the occasional steep hill climb between Moriarty and Tucumcari, but that’s about it.
I-40 widens to six lanes through most of the Amarillo area; for the most part, it runs through the main commercial strip of the city. Leaving Amarillo, I-40 goes right back into the same billiards-table-flat plain that covers thousands of square miles of the Texas panhandle. The highway enters slightly more hilly terrain in Oklahoma, but even most of the way into far eastern Oklahoma, I-40 is still fairly flat. The Ford Center, the temporary Oklahoma City home of the NBA’s New Orleans Hornets, comes almost right up to the edge of I-40 in downtown OKC.
Near the Arkansas border, I-40 enters into the Arkansas River valley. Much of this region of northwestern Arkansas is hilly to mountainous, so I-40 runs through the flattest part of the area — the river valley. There are a few moderately long hills to climb and descend, but the road itself never gets all that terribly hilly. At Conway, I-40 makes a 90° turn to the south, and heads almost due south for roughly 25 miles to the northwest corner of Little Rock. There, it turns back to the east and bypasses the downtown areas of Little Rock and North Little Rock to the north. (Both of these cities can be accessed via westbound Interstate 30.) East of Little Rock, I-40 turns ever-so-slightly to the east-northeast and enters an almost totally flat part of Arkansas (essentially the entire southeastern half of the state is flat).
The next 115 miles or so are spent crossing this flat, largely agricultural area of Arkansas that appears to specialize in the growing of cotton and soybeans. Finally, just north of West Memphis, I-40 meets Interstate 55 for a very short multiplex; some of the cheapest fuel has historically been found here along this I-40/55 multiplex in West Memphis. Five miles of river plain later, I-40 utilizes the Hernando DeSoto Bridge, a true architectural feat designed to look like cataracts on the Nile, to cross the Mississippi River into downtown Memphis. East of the Riverside Drive exit, I-40 is only four lanes through the busiest part of Memphis.
Two miles into Tennessee, I-40 hits the so-called “Midtown Interchange.” The original plans for Memphis’ highway system called for I-40 to continue straight on through the center of the “midtown” area, with the I-240 beltway forming a complete loop around the area. However, the planned route for the I-40 midtown alignment went right through Overton Park, a large urban park that contained, among other things, one of the largest zoos in America and one of Tennessee’s oldest forests. The midtown route was roughly halfway completed when the U.S. Supreme Court issued its Citizens to Preserve Overton Park v. Volpe decision in 1971, effectively halting efforts to build I-40 through the park.
After the Volpe decision, I-40 was then routed along the northern half of the beltway, on a mostly six-lane alignment. However, the exit and mile numbers on the beltway had been set with I-240 in mind, and east of the beltway, they had been set using the planned midtown alignment of I-40. What all of this means is that the exit numbers and mile markers on the Memphis beltway portion of I-40 are roughly two miles too low with respect to the actual mileage from the Arkansas-Tennessee state line (the centerline of the Mississippi River).
The east-side transition off of the beltway adds another 1½ miles to this error, meaning that all I-40 exit and mile numbers east of I-240 in Tennessee are 3½ miles too low; for example, “Exit 204” for Briley Parkway on Nashville’s west side is 207.6 miles from the state line. In attempts to cover up these discrepancies, the first four miles of I-40 (from the river to the Midtown Interchange, and then the next two miles on the beltway) are numbered 0, 1A, 1B, and 1C, and mile number 11 on the beltway segment is immediately followed by a mile number 11B after eastbound I-40 leaves the beltway.
Both Memphis and Nashville, the two largest cities in Tennessee, are well-known in musical circles as being the birthplaces of various musical styles. Memphis is world-famous for Beale Street and the blues, and Nashville is obviously the hometown of country music with the historic Ryman Auditorium and the Grand Ole Opry. For this reason, I-40 between Memphis and Nashville is unofficially nicknamed “Music Highway” by the Tennessee Department of Transportation.
Extreme western Tennessee is fairly flat, but I-40 slowly becomes more and more hilly the further east it goes. Between the Tennessee River crossing at mile 133 and Nashville, this becomes especially noticeable. Just west of Nashville, I-40 widens to six lanes, and stays at six for much of the way through the city. Just outside downtown, along a short multiplex with Interstate 65, I-40 passes right next to the Tennessee State Capitol building as it goes by the west and south sides of the downtown area. Upon meeting Interstate 24 for another multiplex, I-40 widens to eight lanes for a short stretch; it stays at eight lanes past the eastern I-24 split out toward Opryland USA and Nashville’s airport. Near Mt. Juliet, I-40 narrows first to six lanes, then quickly back down to four.
East of Lebanon, I-40 enters into a more mountainous area; there are a few 55 to 60 mph curves here and there that require a wee bit of slowing down. After passing by the town of Cookeville, eastbound I-40 begins a five-mile, 5% climb that takes it up on top of the Cumberland Plateau; the highway remains atop the plateau for roughly 30 miles to Crossville, and then very slowly starts to descend again, taking almost 30 miles to come all the way back down. (The steepest grade coming off the plateau is around 4% for about 3 miles near the town of Harriman.)
The highway passes Oak Ridge, the site of a well-known military laboratory, and eventually joins with Interstate 75 in extreme western Knox County. It widens to six lanes for a few miles, and later eight lanes. At the I-275 interchange in downtown Knoxville, I-40 instantly drops to four lanes; this four-lane stretch is terribly congested and frankly quite dangerous. (It will be closed to traffic for 14 months and reconstructed beginning in May 2008; traffic will be forced to use I-640, the Knoxville bypass, during this time.)
East of the downtown area, I-40 widens once again to six lanes; it remains at six lanes through semi-rural areas all the way out to the Interstate 81 junction near Dandridge. This is due in part to I-40 being the best route from points north and west of Knoxville to the Great Smoky Mountains; that national park can be accessed by using the Tennessee State Route 66 exit (Exit 407) near Sevierville. After I-81, I-40 actually turns more to the southeast and passes by the town of Newport before entering the Smokies itself.
I-40 doesn’t actually pass through Great Smoky Mountains National Park; it runs along the eastern edge of the park. Still, the 27-mile stretch in the Pigeon River Gorge, straddling the Tennessee/North Carolina line, is very rugged and an amazingly scenic, beautiful drive. The entire stretch has very tight curves and bears a 55 mph (88 km/h) speed limit for cars (50 mph or 80 km/h for large trucks). Unfortunately, rock slides off the mountain face occur occasionally, and some of them can close I-40 for as much as a few days at a time. (One such slide that occurred beneath the roadway in 2004, at mile marker 3.5 in North Carolina, had one eastbound lane closed for almost two years.)
At roughly mile marker 19, near Waynesville, NC, I-40 finally exits the Pigeon River Gorge and straightens out considerably, turning back to the east-northeast as it does so. The speed limit is kept down to 60 mph (96 km/h), however, because of the mountainous nature of much of western North Carolina. Roughly 30 miles east of the gorge, I-40 passes to the south of the city of Asheville; the historic Biltmore Estate is accessed by exiting I-40 at U.S. Route 25 (Exit 50). Sixteen miles after that, at mile marker 66, eastbound I-40 begins the treacherous descent known as Old Fort Mountain; this is a 6% grade for roughly six miles, and trucks are limited to 35 mph (56 km/h) on the downgrade due to one insanely sharp curve about halfway down. (There is a slow-vehicle lane in both directions on Old Fort Mountain.)
The highway remains in semi-mountainous territory for about the next 50 miles up to the city of Hickory, and then flattens out somewhat. The current routing of I-40 just south of Winston-Salem was actually built in the 1980s to bypass I-40’s original alignment in the city; the old route through downtown now bears a Business I-40 designation. East of there, I-40 passes through a terribly congested stretch on the south side of Greensboro nicknamed “Death Valley”; until 2004, I-40 shared Death Valley with Interstate 85, but within the next few years, both Interstates will bypass Greensboro further to the south when a new I-40 alignment is completed.
After I-40 joins I-85 east of Greensboro, it widens to eight lanes and stays at eight for the entire current 32-mile length of the multiplex; near Hillsborough, I-40 splits from I-85 and goes back to four lanes for a short stretch. I-40 turns a bit to the southeast and heads toward the state capital of Raleigh, gradually widening as it does so. It loops around the south side of Raleigh’s “Inner Loop” on alignment it once shared with its child, I-440. It breaks off of the loop and almost immediately turns to the south-southeast, spending its final 120 miles heading almost due south through rural areas to its eastern terminus at Wilmington. The I-40 designation actually ends when North Carolina Route 132 joins the highway north of Wilmington.
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