Golden Triangle (Beaumont, Orange, Port Arthur)

The “Golden Triangle” cities of Texas are the three Gulf Coast cities of Beaumont, Orange, and Port Arthur. The term—that some people say originated in the 1940s—has been in print from at least 1965.
 
 
Wikipedia
The Beaumont–Port Arthur metropolitan area is defined by the United States Census Bureau as a three-county region in Southeast Texas, east of the Houston–Sugar Land–Baytown metropolitan area. The area is also known as the Golden Triangle centering on the city of Beaumont and its smaller neighbor, Port Arthur. The “golden” refers to the wealth that came from the Spindletop oil strike near Beaumont in 1901, and “triangle” refers to the area between the cities of Beaumont, Port Arthur, and Orange. According to the 2000 Census, it has a population of 385,090 (though a July 1, 2004 estimate placed the population at 383,443).
     
Handbook of Texas Online
BEAUMONT, TEXAS. Beaumont, the county seat of Jefferson County, is in the northeast part of the county, at 30°05’ north latitude, and 94°06’ west longitude, on the west bank of the Neches River and Interstate Highway 10, eighty-five miles east of Houston and twenty-five air miles north of the Gulf of Mexico. With nearby Port Arthur and Orange, it forms the Golden Triangle, a major industrial area on the Gulf Coast.
     
23 February 1961, Dallas Morning News, section 2, pg. 3:
A new golf tournament, the $22,000 Golden Triangle Invitational, will be held at Beaumont next Nov. 8-12.
     
24 March 1965, Port Arthur (TX) News, pg. 33, col. 1:
The Texas Electronics association of the Golden Triangle will hold its monthly meeting in the Schooner restaurant in Nederland Thursday at 7:30 p.m.
   
16 October 1966, Port Arthur (TX) News, pg. 9E, col. 1 ad:
Serving the
Golden Triangle
and Port Arthur
Since
1909
MERCHANTS
NATIONAL BANK
461 Austin