Baseball is at least 170 years old,

and the first game written of was played in NJ!

The first competitive game was played in 1845 at Elysian Fields in Hoboken.

As per excerpts of a 1990 NY Times account at: 

 http://www.nytimes.com/1990/10/04/nyregion/cooperstown-hoboken-try-new-york-city.html

The discovery was made by Edward L. Widmer, a Harvard student, who was doing research for his doctoral dissertation at the New-York Historical Society on Central Park West.

'Time-Honored Game'

In a copy of The New York Morning News, Mr. Widmer found an account of a game on Oct. 21, 1845, between the New York Ball Club and a team from Brooklyn. Like the 1846 game credited by historians as the first, the earlier game was played at the Elysian Fields, then a bucolic area easily reachable by ferry from Manhattan [[in Hoboken], which was already suffering from overdevelopment.

And the newspaper account of the 1845 game suggests that there had been even earlier contests. ''A friendly match of the time-honored game of Base was played yesterday at the Elysian Fields, Hoboken,'' the article said.

New York won, 24 to 4, aided by a grand slam, or in the vocabulary of the time, ''four aces'' off a single hit.

John Bowman, a co-author of ''Diamonds in the Rough: The Untold History of Baseball,'' said, ''This looks like the first box score and first published newspaper account of a game.''

When Gov. Jim Florio proclaimed ''Baseball Day'' on the previously held June 19th date, based on 1846, he related: ''The truth is that baseball was born here in Hoboken.'' 

Baseball developed from the 18th-century English boys' game of rounders, Dr. Voigt said. Rounders was played in America by soldiers at Valley Forge during the American Revolution. But various regions, including Massachusetts, New York and Philadelphia, initially had their own informal variations of the game, and it was only in the mid-1840's in New York that teams specially organized to play baseball sprang up, formulating a set of rules similar to the modern game.