Some places in Texas are unambiguous. When you’re in say, San Antonio, Marfa or Galveston, you just know it. But in other parts of the state, the boundaries are less well-defined.

For example: How do you know when you’re in West Texas?

Producer Michael Marks set out to tackle this question.

After a long and winding road – that included some pit stops with the Texas Standard staff – he found the answer in a surprising place: a map of oak tree growth in Texas.

And here’s an interactive version of the map.

“You can see a clear line where they just stop,” Marks says. “It’s a sharp edge where there are oaks to the east and none to the west.”

That edge, he thinks, is what separates West Texas from the rest of the state.

Oaks need more rainfall than they can get in West Texas, which is what gives the western part of the state its iconic blend of mesquite trees, red dirt and cowboy culture.

“It starts just east of Wichita Falls, then down to the outskirts of Abilene and San Angelo, then bulging a little further west as you move south,” Marks says of the line of oaks. “So places like Junction, Brownwood and Graham are out. Sonora is teetering right at the edge.”

Listen to the full interview in the audio player above. And tell us where you think West Texas starts by joining the conversation on Twitter. Here’s a few suggestions we’ve gotten so far:

Tell it like it isTweet @TexasStandard or leave a comment here
  • James June 27, 2017 at 8:09 am

    Having grown up in West Texas, El Paso to be precise, and having had to travel the breadth of the state to visit my grandparents in Victoria, I always marveled at the change that happened when I arrived in Ozona. It was green in Ozona. There were TREES! Granted, they were mostly in the dells, but it was GREEN! The flat land between Ozona and Sonora known as the Edwards plateau was noticeably different and it felt like we were driving across the top of the world, especially when we got passed Sonora heading toward Junction. The transition was complete by the time 290 descended into the North Llano River valley heading into Junction. So, where does West Texas begin? On I-10, it’s at the Western edge of the Edwards Plateau.
    On US90, it’s just east of Del Rio. Del Rio’s dry and looks much like what’s west of the Pecos, but heading east it becomes GREEN!
    I admit that I can’t speak for the old US80 route. I had no reason to head up to Dallas, but once. I remember it seemed pretty GREEN around Sweetwater.
    The common theme? If it’s GREEN all over, it NOT West Texas!

  • Robert C Rangel June 13, 2017 at 3:29 pm

    The oak tree line defines the beginning of west Texas. Fort Worth though is where the American west begins.

  • Anonymous June 13, 2017 at 2:08 pm

    There is a shift in soil make up with Waco right on the line. East is good soil and if you go west it is rocky. To me that is the reason for the oak trees and where West Texas starts.

  • Lynn June 13, 2017 at 12:53 pm

    M B has the correct answer, IMO. Mesquite trees are the dividing line.

  • Phototex June 13, 2017 at 12:02 pm

    I consider west Texas to be everything in Texas west of the Pecos River.

  • Bud June 13, 2017 at 7:34 am

    God drew a line where West Texas begins, it’s called he CAPROCK.

  • Chris June 12, 2017 at 11:34 pm

    Shinnery oak (or Havard oak) are shrubs, not trees, and I don’t think anyone could call a bunch of shrubs growing in the desert a forest by any normal definition of the word. And having lived in Texas for 30 years and spent the first 18 of them in West Texas (in the Permian Basin), I’ve never in my life ever heard anyone consider Fort Worth, much less the western portions of Austin or San Antonio, West Texas.

  • Dawn Jones June 12, 2017 at 11:24 pm

    Great

  • Paul Heard June 12, 2017 at 11:23 pm

    Cross the Pecos River and then you are in West Texas. There

  • Steve Digby June 12, 2017 at 9:51 pm

    Although I am not sure what they meant by it, I believe Ft Worth used to promote itself as “Where the West begins.”
    The Oak tree idea is pretty interesting, except for one minor problem, the Harvard oak, often called the shin oak, or shinnery, because they are uaually only shin high. This little tree looks like an oak in color, leaf shape and it even produces acorns. The forest reportedly covers some 40,000 acres in West Texas. I understand the trees are often connected by a common root system. Anyway, if they are truly oak trees, they prefer West Texas. So, you are back to the limited rainfall of less than 20″ to delimit West Texas.
    Additionally, places in West Texas where there is water, such as Big Spring and San Angelo, there are Oak trees.

  • Chad Ober June 12, 2017 at 9:00 pm

    You’ll know when you have reached the west when drivers of oncoming cars wave at you simply because you’re driving too. You’ll begin to initiate the wave a couple hundred miles into the west. If your waves are met by obscene gestures…you have made it to the west coast.

  • Anonymous June 12, 2017 at 7:29 pm

    West Texas is a loosely defined part of the U.S. state of Texas, generally encompassing the arid and semiarid lands west of a line drawn between the cities of Fort Worth and Del Rio.

  • Paul Kevin Smith June 12, 2017 at 6:59 pm

    Driving west from Austin, I always feel I’m in West Texas once I pass Junction. Driving northwest, I would say Brady or Brownwood.

  • M B June 12, 2017 at 6:39 pm

    In a 1940s cowboy-themed movie shot in Fort Worth, TX. The main actors might have been Roy Rodgers and/or Gene Autry, It was proclaimed that “Fort Worth is where the West begins”. I saw that movie on tv in the mid-1950s. It was neat to see Will Rogers Center and other Fort Worth landmarks on tv!
    This was well before I-35W/E was reality, or I-20/30, or the northern growth of Arlington, so the look of the land and how it changed as you drove east from Fort Worth was much more evident. Heading west from Fort Worth, the land looked more like Fort Worth (fewer trees and more open ranch land), so this was the first edge of West Texas . . . where cattle ranching was active.
    I concur, “West Texas” is a state of mind, NOT to be found, especially back then, in Dallas, with all de respect. Fort Worth was “Cowtown” and Dallas was where fancier stores and national offices were.
    Even in the middle 1970s, Fort Worth people were different from Dallas people, as an observation of myself and others (who grew up in “West Texas”).
    Many of your commenters on the segment desired to look at annual rainfall and the vegetation it would or would not support. Rather than the western edge of oak tree populations, I’d look more at the eastern edge of mesquite tree population.

  • Jim Clements June 12, 2017 at 6:23 pm

    West Texas begins in Fort Worth, read the short story by Larry McMurtry.

  • Andy Sanchez June 12, 2017 at 5:10 pm

    The westernmost city used to be El Paso until a little cowtown west of it became officially a town – Canutillo Texas. Across the street from Canutillo is Santa Teresa New Mexico.

  • Jerry Cutright June 12, 2017 at 4:11 pm

    Have y’all ever seen the scrub oak forests in west Texas?

  • Nancy Huston June 12, 2017 at 3:51 pm

    Traveling from Lubbock to Pecos for a job interview 12 years ago, I thought I was quite possibly driving to the edge of the earth. Turns out, it was hell.

  • Colette Pearce June 12, 2017 at 3:35 pm

    So, using the lack of oaks as a basis for determining what is west Texas, does this mean that Jeff Davis county and the Chisos Mountains are NOT in west Texas since the map shows oaks are present there?

  • David Cristiani June 12, 2017 at 3:16 pm

    West Texas begins where it tends to become less humid and green. But for places, west of a line from Langtry to Sonora to Vernon.

  • Anonymous June 12, 2017 at 3:13 pm

    I think you should find out more about the part of Texas you are talking about before you make such statements about oaks. for your information look up where the world’s largest oak forrest is.

    • Anonymous June 12, 2017 at 3:59 pm

      The map is bio mass of Oak Trees. “Largest” oak tree forest is a bit of a misnomer if they’re all stunted shrubs.

  • Paula June 12, 2017 at 3:07 pm

    West Texas is a place but I think it begins in your soul. West Texas is a place! But you also feel West Texas so it might be a little different for each person. For me, West Texas begins in Cowtown (Fort Worth) and moves west through the West Texas communities, the farms, the ranches. West Texas is also in the hearts of all that know it and love it.

  • Eulon Ross Taylor June 12, 2017 at 1:44 pm

    IH-35 & IH 35-W. the hill country and the rest are part of West Texas