I’m not sure when it began, but Discover Lehigh Valley has decided to refer the Allentown-Bethlehem-Easton, PA-NJ metropolitan area as “Lehigh Valley” instead of “the Lehigh Valley.”
I grew up in this area and for as long as I can remember, when the term has been used by locals it’s always been “the Lehigh Valley.” Omitting the “the” makes it sound like Lehigh Valley is the name of a city, like Simi Valley, California, or Golden Valley, Minnesota. There is no city in Pennsylvania named Lehigh Valley. Lehigh is the name of the valley where I live.
You wouldn’t say, “I’m going to Rocky Mountains on vacation,” or, “Let’s go check out wineries in Catskills.” You would say, “I’m going to the Rocky Mountains on vacation,” or “Let’s go check out wineries in the Catskills.”
As my friend Laini said, “When used as an adjective, it doesn’t need the ‘the’. As a noun, technically, it does.”
Example: The Lehigh Valley is home to many festivals like Musikfest, Bacon Fest and Mayfair. Lehigh Valley cities include Allentown, Bethlehem and Easton.
Save the the.