|Lyndon B. Johnson Freeway|
I-635 highlighted in red
|Auxiliary route of I-35|
|Maintained by TxDOT|
|Length||36.999 mi (59.544 km)|
|Existed||October 1, 1959-present|
|Southeast end||in Balch Springs|
|Northwest end||/ near DFW Airport|
Interstate 635 (I-635) is a 37-mile-long (60 km) partial loop around Dallas, Texas, in the United States between I-20 in Balch Springs and State Highway 121 (SH 121) at the north entrance of the Dallas-Fort Worth International Airport in Grapevine. It intersects I-35E at exits 27B-C, but does not connect with I-35W. Portions of I-635 and I-20 are collectively designated as the Lyndon B. Johnson Freeway; known locally as the LBJ Freeway, or simply LBJ. The roadway is named after Lyndon B. Johnson, the former U.S. Senator from Texas, 37th Vice President, and the 36th President of the United States.
Where I-635 ends at I-20, I-20 continues the LBJ Freeway designation heading west.
Because the portion of I-20 between Spur 408 to I-635 retains the same names as I-635, the two highways can be considered 3/4 of the beltway around Dallas. Together with Spur 408, a portion of Loop 12 (Walton Walker Freeway), and a portion of Interstate 35E, the Stemmons Freeway, I-635 and I-20 complete the beltway.
I-635 begins at an intersection with I-20 in southeast Dallas, and travels northward through Balch Springs into Mesquite, where it intersects U.S. Highway 80 (US 80) and I-30. The route then turns to the northwest, continuing near the border between Dallas and Garland. Six miles (9.7 km) later is takes a general westward turn as it intersects US 75 at the High Five Interchange. The section from I-35E to US 75 (Central Expressway) is one of the busiest stretches of road in the Dallas-Fort Worth Metroplex, at virtually all hours of the day and night. The route continues west, intersecting the Dallas North Tollway and its original terminus, I-35E in Farmers Branch. The freeway then continues to the northwest, intersecting the President George Bush Turnpike in Irving before arriving at its final terminus at SH 121 at the north entrance to the Dallas-Fort Worth International Airport.
I-635 was originally designated by the Texas Department of Transportation in 1959 as a loop around the eastern side of Dallas, connecting with I-35E to the northwest and southwest sides of the city.
In January 1969, the first section to open to motorists was a 10-mile (16 km) section from US 75 to Barnes Bridge in Mesquite[clarification needed]. In February 1970, the highway from US 75 westward to I-35E northwest of Dallas opened to traffic. The I-635 designation was truncated on December 2, 1971 when I-20 was rerouted south of Dallas, taking over 13 miles (21 km) of I-635's former route.
The connecting section of I-20 from the west was not completed until 1978. Initially, the section between I-35E and US 80 in southeast Dallas was concurrent with I-20. When the outlet for I-20 from southeast of Dallas to Terrell was completed, the I-635 designation was removed from I-35E to its intersection with I-20.
On April 1, 1968, Texas State Highway Loop 635 was designated from I-35E and I-635 to Spur 459 at the north entrance of DFW Airport. Spur 459 became part of a rerouted SH 121 on July 31, 1969. On July 31, 1974, Loop 635 was redesignated as part of I-635, and this section was opened in the 1980s.
The High Five construction project (so called because it is five levels and rises almost 120 feet (40 m) above the lowest level), a rebuild of the interchange of I-635 and US 75, was opened for traffic in February 2006. This interchange carries over 500,000 vehicles per day and was built as the largest interchange in the state of Texas to handle this vehicle load.
A $2.7 billion project was started on May 16, 2011, to widen I-635 and dig subsequent high-occupancy toll (HOT) lane tunnels beneath the primary roadway from I-35E to the High Five Interchange, a length of 8 miles (13 km). Construction time was estimated in 2011 at five years  and was completed and opened for traffic on September 10, 2015.  The new freeway features tolled express lanes, known as TEXpress lanes, in between the main lanes or underneath them. The cost to drive on them fluctuates based on the current flow of traffic at the time. The project is among several billion dollar plus projects in the planning phase in and around downtown Dallas along with the rebuild of the I-35E & I-30 "Mixmaster". 
|Dallas||Balch Springs||0.0||0.0||-||west - Fort Worth||Southern terminus; exit 480 on I-20|
|0.1||0.16||1C||east - Shreveport||Southbound exit and northbound entrance|
|2.6||4.2||2||Lake June Road|
|Mesquite||3.6||5.8||3||West Cartwright Road / Bruton Road|
|5.0||8.0||4||(Military Parkway / Scyene Road)|
|6.6||10.6||6||- Dallas, Terrell||Signed as exits 6A (west) and 6B (east)|
|8.1||13.0||7A||Towne Centre Drive||Southbound exit and northbound entrance|
|7.5||12.1||7B||Town East Boulevard||Signed as exit 7 northbound|
|8.7||14.0||8||(US 67) - Dallas, Texarkana||Signed as exits 8A (west) and 8B (east); exits 56B-C on I-30|
|9.7||15.6||9A||Oates Drive / Galloway Avenue|
|-||Express Lanes||Southern terminus of Managed HOV Lane|
|Mesquite-Garland line||10.8||17.4||9B||La Prada Drive||Eastbound exit and westbound entrance; signage changes to east-west here|
|Garland||11.4||18.3||11A||Centerville Road / Ferguson Road|
|12.2||19.6||11B||Northwest Highway / Shiloh Road|
|13.4||21.6||12||(Garland Road)||Westbound access via exit 11B|
|Garland-Dallas line||13.9||22.4||13||Jupiter Road / Kingsley Road / Walnut Hill Lane|
|Dallas||-||Express Lanes||Westbound exit and eastbound entrance to Managed HOV Lane|
|15.2||24.5||14||Plano Road / Church Road|
|16.0||25.7||15||Miller Road / Royal Lane||Access to LBJ/Skillman Station|
|16.6||26.7||16||Skillman Street / Audelia Road|
|-||Express Lanes||Westbound exit and eastbound entrance to Managed HOV Lane|
|17.6||28.3||17||Forest Lane / Abrams Road|
|18.2||29.3||18A||Greenville Avenue||Signed as exit 18 westbound|
|-||Express Lanes||Eastbound exit and westbound entrance to Managed HOV Lane|
|-||west||Westbound exit and eastbound entrance; Managed HOV Lane becomes Express Lanes|
|19.5||31.4||18B||TI Boulevard||No westbound exit; full Express Lane interchange; to LBJ/Central Station|
|18.8||30.3||19A||- Dallas, McKinney||High Five Interchange; exit 21 on US 75|
|-||north (HOV) to Spring Creek Parkway||Express Lanes; westbound exit and eastbound entrance|
|20.2||32.5||20||Park Central Drive / Hillcrest Road|
|21.5||34.6||21||(Preston Road) / Montfort Drive|
|Farmers Branch-Dallas line||22.8||36.7||22B||Dallas Parkway / Inwood Road / Montfort Drive||No direct eastbound exit (signed at exit 22D)|
|23.2||37.3||22C-D||Signed as exits 22C (north) and 22D (south)|
|24.1||38.8||23||Midway Road / Welch Road|
|25.2||40.6||24||Marsh Lane||No direct westbound exit (signed at exit 23)|
|25.8||41.5||25||Webb Chapel Road / Josey Lane / Denton Drive / Harry Hines Boulevard|
|Dallas||- Dallas, Denton||Westbound exit and eastbound entrance from Express Lanes|
|27.8||44.7||27B-C||(US 77) - Dallas, Denton||Signed as exits 27B (north) and 27C (south); exits 440B-C on I-35E|
|-||east||Western terminus of express lanes|
|Farmers Branch||29.0||46.7||28||Luna Road|
|Irving||30.0||48.3||29||north||Signed as exits 29 (north) and 30 (south) westbound, 29A (south) and 29B (north) eastbound|
|30.7||49.4||31||MacArthur Boulevard||To Las Colinas Medical Center|
|31.9||51.3||31B||Olympus Boulevard||Eastbound exit via exit 31|
|Coppell-Irving line||32.8||52.8||33||Belt Line Road|
|Tarrant||Grapevine||36.7||59.1||36A||south / - Fort Worth, DFW Airport, Dallas||Westbound exit and eastbound entrance|
|36.9||59.4||36B||north / north (Grapevine Mills Parkway) / Bass Pro Drive||Western terminus|
|1.000 mi = 1.609 km; 1.000 km = 0.621 mi|