The first expansion for Northern Pacific is covering the Southern Pacific Railroad.

The Northern Pacific expansion: Southern Pacific game uses the components found in both the original Winsome Games production of Northern Pacific and the later licensed Rio Grande Games production of Northern Pacific. It may be played by owners of either game.

Provided are two 11×17 inch maps that must be trimmed on the short edge, resulting in an 11×33 inch game board.

The Northern Pacific expansion: Southern Pacific is for 3-6 players and takes as long as a Northern Pacific game. There are no rules changes.