The Origin of "Kilroy Was Here!"-Unproven!

Summary of the eRumor:
An account of how the World War II slogan and cartoon "Kilroy Was Here" came into being.  It is credited to a Massachusetts man named James Kilroy who was allegedly identified through a nationwide contest sponsored by the American Transit Association.  Kilroy is said to have been a shipyard worker during the war who scribbled his graffiti on a lot of ships that went to war.
The Truth:  
The "Kilroy Was Here" scribble and the cartoon that accompanied it became widely known during World War II.  Kilroy became a symbol of the presence of American GI's and a smiling suggestion that he had gotten there first.  The "Kilroy Was Here" graffiti was seemingly everywhere.

There is not agreement as to where and how "Kilroy Was Here" got started although the story of James Kilroy certainly deserves attention.  The radio contest by the American Transit Association did actually take place and James Kilroy was the only one out of 40 people who responded who seemed to be able to back his story of having originated it while he was an inspector at the Fore River Shipyard in Quincy, Massachusetts.  He produced coworkers who backed up his story and pointed to Kilroy cartoons that appeared in obscure portions of ships that could have only been put there by a shipyard worker.

Although the popularity of Kilroy peaked in the 1950s he's still around.  He's been known to have been found scribbled by American soldiers in obscure places in Iraq and Afghanistan.

Updated 2/16/08
A real example of the eRumor as it has appeared on the Internet:

KILROY WAS HERE!

In 1946 the American Transit Association, through its radio
program, "Speak to America," sponsored a nationwide contest to find the
REAL Kilroy, offering a prize of a real trolley car to the person who
couldprove himself to be the genuine article.
Almost 40 men stepped forward to make that claim, but only James
Kilroy from Halifax, Massachusetts had evidence of his identity.
Kilroy was a 46-year old shipyard worker during the war. He
worked as a checker at the Fore River Shipyard in Quincy. His job was to
go around and check on the number of rivets completed. Riveters were on
piecework and got paid by the rivet.
Kilroy would count a block of rivets and put a check mark in
semi-waxed lumber chalk, so the rivets wouldn't be counted twice. When
Kilroy went off duty, the riveters would erase the mark.
Later on, an off-shift inspector would come through and count
the rivets a second time, resulting in double pay for the riveters.
One day Kilroy's boss called him into his office. The foreman
was upset about all the wages being paid to riveters, and asked him to
investigate. It was then that he realized what had been going on.
The tight spaces he had to crawl in to check the rivets didn't
lend themselves to lugging around a paint can and brush, so Kilroy
decided to stick with the waxy chalk. He continued to put his checkmark
on each job he inspected, but added KILROY WAS HERE in king-sized
letters next to the check, and eventually added the sketch of the chap
with the long nose peering over the fence and that became part of the
Kilroy message. Once he did that, the riveters stopped trying to wipe
away his marks.
Ordinarily the rivets and chalk marks would have been covered up
with paint. With war on, however, ships were leaving the Quincy Yard so
fast that there wasn't time to paint them.
As a result, Kilroy's inspection "trademark" was seen by
thousands of servicemen who boarded the troopships the yard produced.
His message apparently rang a bell with the servicemen, because they
picked it up and spread it all over Europe and the South Pacific. Before
the war's end, "Kilroy" had been here, there, and everywhere on the long
haul to Berlin and Tokyo.
To the unfortunate troops outbound in those ships, however, he
was a complete mystery; all they knew for sure was that some jerk named
Kilroy had "been there first." As a joke, U.S. servicemen began placing
the graffiti wherever they landed, claiming it was already there when
they arrived.
Kilroy became the U.S. super-GI who had always "already been"
wherever GIs went. It became a challenge to place the logo in the most
unlikely places imaginable (it is said to be atop Mt. Everest, the
Statue of Liberty, the underside of the Arch De Triumphe, and even
scrawled in the dust on the moon.)
And as the war went on, the legend grew. Underwater demolition
teams routinely sneaked ashore on Japanese-held islands in the Pacific
to map the terrain for the coming invasions by U.S. troops (and thus,
presumably, were the first GI's there). On one occasion, however, they
reported seeing enemy troops painting over the Kilroy logo! In 1945, an
outhouse was built for the exclusive use of Roosvelt, Stalin, and
Churchill at the Potsdam conference.
The first person inside was Stalin, who emerged and asked his
aide (in Russian), "Who is Kilroy?" ...
To help prove his authenticity in 1946, James Kilroy brought
along officials from the shipyard and some of the riveters. He won the
trolley car, which he gave to his nine children as a Christmas gift and
set it up as a playhouse in the Kilroy front yard in Halifax,
Massachusetts.

So now You Know!