i cant find any subways in new vegas can some people tell me where to find some?

also how do i find the quest to clear out the ncr correctional facility?

Nope, no subway. No need for one.

One it's in the northen part of the map, but very small.. Just like stonehenge on stage, or the Mona Lisa.

2. Do the quests for Eddy ( the PG's boss. )
When asked to scout out the NCR at Primm, tell the LT that you'll help him kill the gangers.

no ime missing something i have cleared out primm and got primm the ncr as a sheriff but dont have a quest for the correctional facility?

were do i find eddy and whats the pg?

i cant do quests for the boss of the pgs powder gangers because they hate me so how do i get the quest to wipe them out??

The only way you can get that quest is from Eddy.

You can always try to use Powder Ganger faction armor or wipe them out without the quest.

(In case you didn't know, faction armor resets your rep for that faction.)

There are some sewers under NV to explore, but it is nowhere near as good as the subway system under DC.

Use a powder ganger disguise and enter the prison. Go to the northern building in the courtyard. I don't know if they'll play nice once you vilified. If they're not hostile Eddy has some quest for you the final one is looking for information about an attack on the prison. That information opens up the quest to help the NCR.