The North Sewers is a section of the New Vegas sewer system that is inhabited by poorer outer New Vegas citizens for shelter. It is relatively safe as it is free of dangerous creatures and raiders. The sewer connects to the Central sewers via pipeline in the south, and to the fighting arena of The Thorn in the west. There are several exits to the settlements around New Vegas via manholes in the north section of the sewer. On your map most exits are labeled Mojave Wasteland except those for Westside and North Vegas Square, this is because these exits are inside the walls of these settlements. The location of the exit is mentioned however when looking at the ladders. The exits that are labeled Mojave Wasteland from left to right on your map are: North Vegas (just outside the settlement, very near the H&H Tools Factory), Freeside's north gate and the Crimson Caravan Company. Greasy Johnny can be found in the west portion of the sewer.
xbox360 Sometimes entering through the manhole in North Vegas Square will cause companions to become stuck. They will not be visible or able to follow you through the area, though upon exiting they will reappear and begin to follow you again. Entering through The Thorn causes no problems. [verified]
xbox360 A humorous bug can occur where citizens can be seen swimming mid-air above the platforms in the same room as the East Central Sewers manhole. [verified]