Jackson Whipps Showalter (February 4, 1860, Minerva, Ohio – February 6, 1935, Lexington, Kentucky) was a five-time U.S. Chess Champion: 1890, 1892, 1892–1894, 1895-1896 and 1906–1909. He was born in Minerva, Kentucky.
He won U.S. Championship matches against S. Lipschütz (twice), Max Judd and Albert Hodges. He lost championship matches to Lipschütz, Max Judd, Harry Nelson Pillsbury, and Frank Marshall.
He was known as "the Kentucky Lion" after his birthplace and his hairstyle, which consisted of a thick mane down the back of his neck, and perhaps also his playing strength.[1]
The variation of the Queen's Gambit Accepted. 1. d4 d5 2. c4 dxc4 3. Nc3 is named after him.
The famous "Capablanca Simplifying Manoeuvre" in the Orthodox Variation of the Queen's Gambit Declined (1.d4 d5 2.c4 e6 3. Nc3 Nf6 4. Bg5 Be7 5. e3 Nbd7 6. Nf3 0-0 7. Rc1 c6 8. Bd3 dxc4 9. Bxc4 Nd5) had in fact been used by Showalter in the 1890s

As far as I know there are no books on J. W. Showalter.
See ^ David Hooper and Kenneth Whyld, The Oxford Companion to Chess (2nd ed. 1992), p. 371. ISBN 0-19-866164-9. (From Wikipedia.org)
The Encyclopedia of Chess Vol. I does not cover the Showalter era.
They never made a Volume II.
References:
The Campbell Report.
"The Postal Lion: Jackson Showalter and Correspondence Chess" by Neil R. Brennen
With photos and notes to Showalter games.

Photos and history:
Jackson Whipps Showalter - Chess Champion, Curve Ball Proponent, Cigar Aficionado

Lasker is defeated. No not Em. Lasker but Ed Lasker:
http://query.nytimes.com/mem/archive...BE668389639EDE
American Chess Bulletin - Google Book Search

Max Judd article with reference to Jackson Showalter
Max Judd

An interesting article with photos:
The oldest Chess book ever printed or written in U.S. was Chess Made Easy
1802.
http://www.franklin-mercantile.com/r...ub+History.pdf

Book Reference:
Chess in Philadelphia: A Brief ... - Google Book Search

The Marshall-Showalter Match 1909.
Marshall

A Showalter article in German. From the Berliner Zeitung Archiv 2007
Jackson W. Showalter : Textarchiv : Berliner Zeitung Archiv

Now was this Jackson W. Showalter's wife. Probably so:
In the December 6, 1894 issue of the Fort Wayne newspaper, an article appeared called Two Queens of Chess. It states that Mrs. Jackson W. Showalter has long been considered the lady chess champion of America. On November 5, 1894 she began a 7 game match with Mrs. Harriett Worrall (1836-1928) of Brooklyn.

On Samuel Lipschutz who lost a match to Showalter in 1890.
Samuel Lipschutz (1863-1905) - Chess.com

The 1904 Cambridge Springs Tournament.
Showalter came in 5th. (Competition: Marshall, Janowski,Lasker, Marco,
Tchigoran, schlechter, Mieses, Pillsbury and many more. All the games.

The Games of Jackson Showalter
The chess games of Jackson Whipps Showalter

Record:
1890 – Champion – CHAMPIONSHIP OF UNITED STATES.
1894 – Champion – CHAMPIONSHIP OF UNITED STATES.
1895 – Champion – CHAMPIONSHIP OF UNITED STATES.
1906 – Champion – CHAMPIONSHIP OF UNITED STATES.

The Deseret News. - Google News Archive Search

A protest against Pillsbury and Showalter (they played a match):
http://www.chesscafe.com/text/skittles229.pdf

1897 Franklin - Manhattan Chess Club Telegraphic Match
Chess Archaeology

11th Congress of the German Chess Federation
http://www.textfiles.com/games/CHESS/1898colo.xtb
Showalter won 7th prize.
The above appears to be where the search engine stops.

Is this the same person as JWS here?

Yes. The ghost of someone who died in 1935 posts here regularly.

--Fromper

Obviously. Seems quite common to have ghosts posting in forums.

I kind of meant: "Is that the same person that JWS here is named after?", but I was apparently not specific enough. I apologize.