The well known United States airline American Airlines said that it plans to add 23 more flights to and from seven new destinations out of New York’s JFK and LaGuardia airports by the end of the year. The carrier, which is based out of Forth Worth, Texas, has also pledged more than $30 million in terminal improvements at the two airports.

Now, combined with earlier announcements, American Airlines and its sister carrier, American Eagle, will be adding 31 total flights and 13 additional routes to and from the two airports by the end of 2010. American Airlines is also partnering with JetBlue to offer their passengers connections to American’s international flights in and out of New York and Boston.

JetBlue customers will be able to connect to flights to 12 of American’s international destinations from JFK and Boston. On the routes where the carriers do not already compete, American Airlines customers can book nonstop JetBlue flights from JFK and Boston to 18 domestic spots.

As part of this great deal, American Airlines will transfer eight slot pairs at Ronald Regan National Airport and one slot pair at Westchester Airport in White Plains, New York to JetBlue. In exchange, JetBlue will be transferring 12 slot pairs at JFK to American Airlines. A slot is an interval of time during which an airline can takeoff or land at an airport.

JetBlue said that they plan to launch services at Regan National Airport in November. The airline said just this past Wednesday that it will offer at least eight daily departures from Regan to East Coast cities.