“Golden Triangle” usually means the Texas cities of Beaumont, Orange and Port Arthur. Some now consider “Golden Triangle” to mean the largest Texas cities of Dallas, Houston, and San Antonio.
 
Other nicknames for these three large Texas “Golden Triangle” cities include “Texas Triangle,” ‘Texas Trifecta” and “Texas Three-Step.”
   
     
Southwest Airlines
In 1966, Herb Kelleher was practicing law in San Antonio when a client named Rollin King proposed starting a short-haul airline similar to California-based Pacific Southwest Airlines. The airline would fly the Golden Triangle of Houston, Dallas, and San Antonio, and by staying within Texas, avoid federal regulations. 
 
Office of the President, UT-Austin
Knowledge is Power: The Role of the University of Texas in Regional Economic Development
Presented at the Second Chinese-Foreign University Presidents Forum
Beijing, China
August 9, 2004
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About two-thirds of the people of Texas are concentrated in a “Golden Triangle” connecting Dallas-Fort Worth on the north, Houston in the southeast, and San Antonio in the south. There are also large populations on the border with Mexico, one in El Paso, in the far west, and another in the Rio Grande Valley, in the far south.
 
Austin – on the western leg of the Golden Triangle, between Dallas and San Antonio – is the capital of Texas and, of course, the seat of The University of Texas at Austin. From its central location, the University is able to serve people and organizations statewide, and it has many interactions in the major population centers of the Golden Triangle.
   
Horseshoe Bay Resort
Horseshoe Bay Resort is located in the very heart of Texas and is ideally located inside what is known as the Texas Golden Triangle… An area formed by the major Texas cities of Houston, Dallas and San Antonio. Austin, the state capitol, is less than an hour’s drive from Horseshoe Bay Resort. The Golden Triangle of Texas contains some two-thirds of the State’s wealth and population, all within one tank of gas away!
   
Do Something - Endure Life
Friday, October 27, 2006
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The original idea (which I was reminded of after reading a post from our own long lost Jon Walk), was a marathon AND MS150 ride in each of the 3 big cities of the Texas Golden Triangle (Houston, Dallas, San Antonio).
   
Travel Insider
You also mention what could be a ‘golden triangle’ of railroading - Dallas - Houston - San Antonio (and, for that matter, Austin also on the return leg between San Antonio and Dallas). This triangle is brilliantly suited for train service - three (or four or five depending on if you count Ft Worth and Austin, even Waco) major cities all in close proximity to each other such that any one city is less than 250 miles away from any of the other cities. If this was Europe, you’d see high speed trains zipping around and around this large loop, in both directions, almost continuously from early in the morning until late at night. Instead, Amtrak offer one train a day between Dallas and San Antonio, and it takes the train 9hrs 40 minutes to make the journey!