“Longviewite” is the name of an inhabitant of Longview, Texas. “Longviewer” is a likely Longview name, but this is not used in the Longview (TX) News-Journal.
 
The name “Longviewite” has been cited in print since at least 1886.
 
   
Wikipedia: Longview, Texas
Longview is a city in Gregg and Harrison Counties in the U.S. state of Texas. As of the 2010 Census, the population was 80,455. Most of the city is located in Gregg County, of which it is the county seat; only a small part extends into the western part of neighboring Harrison County. It is situated in East Texas, on the grid of Interstate 20 and U.S. Highways 80 and 259, just north of the Sabine River. Longview is a commercial hub for the Longview Metropolitan Statistical Area.
 
Longview is the principal city of the Longview Metropolitan Statistical Area, which is part of the larger MSA made up of Gregg, Upshur, and Rusk counties (population 271,669). Longview is considered a major hub city in the region, as is the nearby city of Tyler.
 
16 August 1886, Dallas (TX) Morning News, “Doings of the Beau Monde,” pg. 2, col. 3:
A great many Longviewites attended the interstate drill at Galveston last week.
 
4 June 1887, Galveston (TX) Daily News, pg. 2, col. 3:
Longview.
LONGVIEW, Tex., June 3.—A few weeks ago several Longviewites bought large amounts of property in Carthage, anticipating the enhancement of values certain to follow the extension of the Galveston, Sabine and St. Louis railroad at that point.
 
30 November 1887, Dallas (TX) Morning News, “Longview Locals,” pg. 4, col. 6:
Those Longviewites who attached the Doris & Colvin Circus at Mineola got a cage of lions and a chariot.
 
3 September 1937, The Kansas-American (Topeka, KS), pg. 5:
Longviewites Feted At Dallas Party
(Longview, KS—ed.)
 
Straight Dope Message Board
snailboy
02-05-2006, 10:42 PM
It’s so much easier naming people from a certain state. Usually you just add -n or in a few cases, -er. What’s the deal with cities though? Is there a pattern to it? For instance, people from my hometown of Beckville are called Beckvillians, and people from the nearby town of Carthage are called Carthaginians (spelling?). I would guess that people from Longview are called Longviewers, though I’ve never heard the term.
     
Google Books
Longview
By Van Craddock
Charleston, SC: Arcadia Pub.
2010
Pg. 51:
Only a week prior to the fire, a number of Longviewites had gathered atop the building to witness the very first airplane, an Army trainer from Fort Worth, fly over downtown, and land in a nearby field.
 
Longview (TX) News-Journal
‘Christmas Carol’ dinner: Time to cook your goose
By Charlotte Stewart
Posted: Wednesday, December 22, 2010 12:00 am | Updated: 12:58 am, Wed Dec 22, 2010.
(...)
Longtime Longviewite Gayle Speegle has a hint for people who find goose too greasy.
 
Longview (TX) News-Journal
Ready-to-go breakfast saves time
By Barbara McClellan
Posted: Wednesday, December 21, 2011 4:00 am | Updated: 7:22 am, Wed Dec 21, 2011.
(...)
If you want a quick and easy bread to serve (not sweet), this time-honored recipe from former Longviewite Nancy Wright is the one for you.