“Flushingite” is the name of an inhabitant of Flushing, in the borough of Queens. The name “Flushingite” has been cited in print since at least 1888.
 
 
Wikipedia: Flushing, Queens
Flushing, founded in 1645 as one of the first Dutch settlements on Long Island, is a lower, middle, and upper middle class and commercial neighborhood in the north-central region of the New York City borough of Queens, in the United States.
 
Flushing’s diversity is reflected by the numerous ethnic groups that reside there, including people of Asian, Hispanic, Middle Eastern, European, and African American ancestry as well as Jewish peoples. It is part of the Fifth Congressional District, which encompasses the entire northeastern shore of Queens County, and extends into neighboring Nassau County. Flushing is served by five railroad stations on the Long Island Rail Road Port Washington Branch, and the New York City Subway IRT Flushing Line (and thus the 7 train) has its terminus at Main Street. The intersection of Main Street and Roosevelt Avenue is the third busiest intersection in New York City, behind only Times Square and Herald Square.
 
Old Fulton Post Cards
7 April 1888, The Comet (Flushing, NY), pg. 1, col. 3:
After picking his way along the muddy sidewalk on Parsons avenue, ye scribe at last came within sight of a large building ahead, which is known to every Flushingite as “The Flushing Hospital and Dispensary;” the result of years of hard labor on the part of the ladies of this village.
 
Old Fulton Post Cards
22 September 1888, The Comet (Flushing, NY), pg. 5, col. 1:
That many Flushingites are now returning from their outings at the Sea-side, or in the Mountains.
 
13 June 1894, New York (NY) Times, “Among the Wheelmen”:
Al Morison, George Butler, and Louis Master are three Flushingites each exceeding 200 pounds in weight, and all bicyclists, representing nearly as much in ...
 
18 August 1896, New-York (NY) Daily Tribune, “Flushing and College Point,” pg. 16, col. 5:
Captain L. B. Freeman, the wealthy Flushingite, who died at his home in Whitestone last week, left no will, and the property which consists principally of real estate and is valued at over $60,000, will be divided among Captain Freeman’s sister, Mrs. Hoffman, of New-York, and his seven nephews.
   
Google Books
The Boroughs of Brooklyn and Queens, Counties of Nassau and Suffolk, Long Island, New York, 1609-1924
By Henry Isham Hazelton
New York, NY: Lewis Historical Pub. Co. Inc.
1925
Pg. 986:
It had been there for nearly a century, and was not only known to Flushingites as one of its relics of the past, but was used by old-timers to designate distances, journeys being so far or in such a direction from the “Red Barracks.”
 
New York (NY) Times
NEIGHBORHOOD REPORTS: QUEENS UP CLOSE; Good Names Are Recovered
By RICHARD WEIR
Published: August 23, 1998
(...)
’‘I live in Woodside,’’ declared an indignant Dorothea Osbourne in a letter to The Tribune. ‘‘And I do not wish to be a Flushingite.’‘
 
Google Books
Becoming American, Being Indian:
An Immigrant Community in New York City
By Madhulika Shankar Khandelwal
Ithaca, NY: Cornell University Press
2002
Pg. 22:
Many former Flushingites combined these ethnic activities in visits there and reserved Jackson Heights shopping for special occasions.