Champ Car and the Indy Racing League have signed a breakthrough deal to merge their series with immediate effect.
Following talks over the past few days to try and close a deal to unify the two series, a statement was issued on Friday night confirming that an agreement had been reached between Champ Car chiefs and the IRL.
The short statement said: "Owners of Champ Car and the Indy Racing League completed an agreement in principle Friday that will unify the sport for 2008.
"Gerald Forsythe, co-owner of Champ Car, signed an agreement in principle in Chicago, joining his partner Kevin Kalkhoven and Indy Racing League founder and CEO Tony George who had signed late Thursday in Indianapolis.
"Details of a press conference about the agreement will be forthcoming."
The deal brings to an end more than 10 years of rivalry between the two North American single-seater series.
It is not confirmed yet how many Champ Car teams will join the IRL, or which events will join a likely expanded calendar this season.
IndyCar team owner Bobby Rahal was one of the first leading figures to announce his backing for the move.
"This is a great day for open-wheel racing and one that I and my Rahal Letterman Racing team have looked forward to for a long time," Rahal said in a statement.
"I applaud all of those that made this possible, but want to especially recognize all of those that made sacrifices and concessions to secure the future of open-wheel racing.
"I truly believe that this is the first step toward restoring open-wheel racing and the Indianapolis 500 to not only where it once was, but beyond."
Derrick Walker, the owner of Champ Car outfit Walker Racing, added that he was delighted the merger has been sealed.
"It's back to the future," he said. "It's been a long road, but it has finally come together. One open-wheel racing series in the United States has long been recognized as what fans and sponsors want to have, and I'm happy to say that Walker Racing embraces the decision.
"I also want to give a special thanks to all the past and present CART/Champ Car officials for all their hard work in giving us some great seasons."