On Thursday, the second of four Abraham Lincoln bicentennial pennies will be unveiled in Lincoln City, Indiana.To celebrate Lincoln's 200th birthday, four pennies are being put into circulation. The first depicts Lincoln's boyhood log cabin and was introduced in Hodgenville in February. The second penny shows Lincoln as a young man in Indiana and the third commemorates Lincoln's days as a lawyer in Illinois. The final penny will depict an unfinished Capitol Dome and will be introduced in November.U.S. Mint spokesperson Greg Hernandez says after all of the pennies have been printed, a new design for the back of the coin will be put into place."Obviously 2009 will be the four aspects of Lincoln's life," he says. "2010 will have a different tails going forward and obviously it'll be up to Congress to determine what will be on the back of the Lincoln Penny for years to come."Hernandez says about 635 million of the first two Lincoln Bicentennial designs will be made.