Cardiff, which has reached the F.A. Cup final, and Swansea, which has secured promotion to the second-tier Championship, will be the only Welsh clubs in the 92-team Football League in next season. Wrexham will play in the Blue Square Premier.
In the other league games played on Tuesday Championship Wolves kept their play-off hopes alive but ended Cardiff's with a 3-0 win at Molineux.
Andy Keogh put the home side ahead with his 11th goal of the season after eight minutes heading home Kevin Foley's cross from the right.
Sylvan Ebanks-Blake added a second just before the break and was involved in the third on 56 minutes.
He forced a save from Peter Enckelman and Michael Kightly pounced first for the rebound.
In League One Swindon defeated Bristol Rovers 1-0 in the mid-table derby. Simon Cox's 74th minute header won the away team the game.