Arlen is a fictional small town in Texas, located in Heimlich County, and named for fictional Leland "Goose" Arlen. It is located about 96 miles from Dallas according to a sign seen in the episode "It Aint Over 'till The Fat Man Sings" while Bill Dauterive drove there with his all-male chorus. It has a population of 145,300 people according to a sign seen in the episode "Hank's Cowboy Movie," where Hank and Bobby return from the Cowboys training camp in Wichita Falls, and in Season 2 episode "Snow Job" the population is 1,454.
In the episode "That's What She Said", Hank is seen driving a Strickland Propane truck. The phone number on the door begins with the area code 409. This area code includes the cities of Beaumont and Galveston.
The name of the town used to be called "Harlen" in the past, which came from the even further back name "Harlottown", which Peggy discovers from old newspapers. Apparently "People were in such a hurry to get to Harlottown that they didn't have enough time to call it such." It was also the site of the AVA(Adult Video Awards) as shown in the episode Harlottown.
Seen in "Revenge of Lutefisk," the town has members of four religions: Buddhism (Theravada), Catholicism, Methodism and Judaism; other religions like Omega House cult, The Coven of Artemis and few unnamed places with elements of functioning religions exist in smalls numbers.
There is also Arlen University ("The Arrowhead ")
Creator, Mike Judge, intended for Arlen to be based on his childhood experiences in the Dallas suburb of Garland, with intermingled names of other Dallas-area cities like Allen, Texas.
In the show, Arlen is portrayed as being in Central Texas. A few maps that showed up in different episodes and dialogue state that Arlen borders or is near towns like Belton, Killeen, and Temple. As well as being along the Brazos River. This would seem to imply Arlen's location to be within the Killeen-Temple-Fort Hood Metropolitan area.