Master of the Mojave

 is an achievement in Fallout: New Vegas which is awarded for successfully discovering 125 locations.

This can easily be obtained by choosing the Explorer perk, which shows all locations on the map, making it easy to quickly find the 125 locations needed.

You can check how many locations you have discovered simply by looking it up in the 'Stats' tab on your Pip-Boy.

Tips
Finding locations in DLC (Downloadable Content) Add-Ons will also count towards this, but are not necessary; making this achievement incredibly easy if you're looking to complete all of the DLCs in one save game.

Bugs

 * Occasionally when the achievement does not appear at the 125th location it can still be obtained by finding more locations.