State Highway 66 or SH 66 is a state highway running from Garland

Garland, Texas

-Climate:* The average warmest month is July.* The highest recorded temperature was in 2000.* On average, the coolest month is January.* The lowest recorded temperature was in 1989.* The maximum average precipitation occurs in May....

 to Greenville

Greenville, Texas

Greenville is the county seat, and the largest city, of Hunt County, Texas, in the United States. As of the 2010 census, the city population was 25,557....

, roughly parallel to Interstate 30.

History

SH 66 was previously designated first in 1926 as a route from Bogata northeast through Clarksville toward the Oklahoma town of Idabel. By 1933, this route had been added as a northern extent of SH 37

State Highway 37 (Texas)

State Highway 37 is a state highway that runs from the Oklahoma border near Albion to Mineola in the northeast corner of the state.-Previous Route:...

, and was instead assigned along an ambitious route spanning the entire state from Wichita Falls

Wichita Falls, Texas

Wichita Falls is a city in and the county seat of Wichita County, Texas, United States, United States. Wichita Falls is the principal city of the Wichita Falls Metropolitan Statistical Area, which encompasses all of Archer, Clay and Wichita counties. According to the U.S. Census estimate of 2010,...

 to the Rio Grande near Hidalgo

Hidalgo, Texas

Hidalgo is a city in Hidalgo County, Texas, United States. The population was 11,198 at the 2010 census. It is home to the Rio Grande Valley Magic of the Southern Indoor Football League, the Rio Grande Valley Killer Bees of the Central Hockey League, and the Rio Grande Valley Vipers of the NBA...

. In 1939, this entire second route was cancelled in favor of U.S. Highway 281.

The current route was designated in 1961, replacing FM 7

Farm to Market Road 7

-History:FM 7 was originally designated in 1942 as a highway from Lipan to US 281, replacing Spur 108. It extended southeast to Granbury in 1945 . This route was replaced in 1948 by FM 4....

 and U.S. Highway 67, which was rerouted atop I-30.

Major intersections

County	Location	Junction	Notes
Dallas Dallas County, Texas As of the census of 2000, there were 2,218,899 people, 807,621 households, and 533,837 families residing in the county. The population density was 2,523 people per square mile . There were 854,119 housing units at an average density of 971/sq mi...	Garland Garland, Texas -Climate:* The average warmest month is July.* The highest recorded temperature was in 2000.* On average, the coolest month is January.* The lowest recorded temperature was in 1989.* The maximum average precipitation occurs in May....
Rockwall Rockwall County, Texas As of the census of 2000, there were 43,080 people, 14,530 households, and 11,972 families residing in the county. The population density was 334 people per square mile . There were 15,351 housing units at an average density of 119 per square mile...	Rockwall Rockwall, Texas Rockwall is a city in Rockwall County, Texas, United States, and a suburb of Dallas. It is part of the Dallas/Fort Worth Metroplex. The population was 37,490 at the 2010 census. It is the county seat of Rockwall County. Rockwall County is the second wealthiest county in the state of Texas in terms...
Collin Collin County, Texas As of the census of 2000, there were 491,675 people, 181,970 households, and 132,292 families residing in the county. The population density was 580 people per square mile . There were 194,892 housing units at an average density of 230 per square mile...			no intersections
Hunt Hunt County, Texas As of the census of 2000, there were 76,596 people, 28,742 households, and 20,521 families residing in the county. The population density was 91 people per square mile . There were 32,490 housing units at an average density of 39 per square mile...	Greenville Greenville, Texas Greenville is the county seat, and the largest city, of Hunt County, Texas, in the United States. As of the 2010 census, the city population was 25,557....