...EXCURSION TO CONEY ISLAND.--A brilliant private pic-nic, comprising some forty ladies and gentlemen, "came off" at Coney Island yesterday. There were three omnibus loads of them--part from the great Gomorrah on the other side of the river. They had a "first rate time," we are informed.
--Brooklyn Daily Eagle, Friday, July 24, 1846
Normon Mailer: An American Aesthetic states "Whitman described Manhattan as 'Gomorrah on the other side of the River'..." Interesting, but why in the world...
The Walt Whitman Archive informs us that Walt Whitman was the editor of the Brooklyn Daily Eagle from March 1846 to January 1848. This appears to be the first use of the phrase in the Brooklyn Daily Eagle. Mystery solved!
January 17, 1857 the Eagle referred to "the Sodom across the river". Later,
The Providence Journal expresses the opinion that if New York city does not disappear some night, and the sound steamers find themselves sailing into a new Dead Sea, people will not believe the account of Sodom and Gomorrah.
--Brooklyn Daily Eagle, Monday, Jun 01, 1857
It wasn't until 1859 that the label drifted to Brooklyn, albeit sarcastically:
Those who have labored under the fallacious idea that Brooklyn was somewhat of a moral community, a "City of Churches" par excellence, will be astounded to learn that it is a perfect Sodom or Pandemonium, with half its population going to perdition and 12,300 of them drunken sots. It will probably relieve such apprehensions to know that from the Report of the Police authorities of the city for the quarter ending 31st of January, it appears that the whole number of arrests for the period were 3,368, of which only 1342 were "directly" from intoxication, and it is well known to the police that the same persons are arrested over and over again during the quarter. The number of disorderly characters arrested was 191 and these may be set down as originating in intemperance; but even these added to the others come short of one half of the tremendous statistics of Mr Hall. We are not insensible to the evils of intemperance, but we would beg leave to suggest that monstrously exaggerated statements of the immorality existing among us, however, necessary to secure votes or cash contributions are an injury to the fame of the city, give us a bad game abroad, depreciate the value of property and are moreover a violation of the precept that forbids the baring of false witness against a neighbor, whether that neighbor be an individual or a whole community.
--Brooklyn Daily Eagle, Friday, February 11, 1859
The New York Times' first use of "Sodom-by-the-Sea" to refer to Coney Island dates October 15, 1893. But there was an similar reference, albeit not a catchy one, buried deeper in an article 20 years prior:
"A few adventurous spirits had even more harrowing stories to tell of perils encountered at Coney Island from sharks of land and water, and the fatal fascinations of three-card monte, until the innocent City youth shuddered at the place as a marine Sodom and Gomorrah..."
--The New York Times, September 29, 1873
Speaking of Gomorrah, in 1848, there were a lot of advertisements for:
Grand Combination of Hanington's Sacred Dioramas of the Creation of the World, and the grand spectacle of THE DELUGE--Also, 22 Magnificent Scriptural Paintings by Mr. BAKER, of London, each one containing about 100 square feet of canvas...
Such scenes included the "Destruction of Sodom and Gomorrah, Gen xix".
Price of admission to the whole, 25 cents--Children half price. Doors open at 7, curtain rises at 7 1/2 o'clock.
EVERY NIGHT THIS WEEK
WEDNESDAY and SATURDAY afternoons, commencing at 3 o'clock, at the splendid new Hall, 396 Broadway, corner of Walker street.
--Brooklyn Daily Eagle, Monday, October 2, 1848 (similar ads through November 25, 1848)