Transportation Markers are used to move (fast travel) from one location to another location in Red Dead Redemption Multiplayer. It is basically the same as using stagecoaches in Single Player, though these are like portals that teleport the player to locations.
The player can also select a specific location by going into the map in the Pause Menu, adding a waypoint, then using the Transportation Marker and selecting Waypoint. When transporting to a gang hideout, the waypoint should be placed a little outside of the hideout area or else the player will find themselves immediately in the middle of the action.
The Transportation Markers appear on the map as a wagon wheel icon. Every major settlement has a transportation marker.