I came across a place called "Northern Passage" which is at the very north of the map and I try to leave the opposite end of the Mojave Wasteland but it won't let me leave. Is this bugged, or is this the location for a future DLC or something? The reason I'm asking is because it's at the end of the wasteland so that's a possibility. The way it's designed leads you to the exit. Also, there is a rock which says "The sun is killing me!" which could refer to Elijah when he tried to hold the sun in his hands (HELIOS One), could this be the way to the Big Empty?

I'm not even going into the speculation part of this. Wait until the next DLC announcement after the major patch.

As for it being locked down, it is intentionally put there.

It's a standard hollowed-out rock, they're allover the place.

Northern Passage is reserved as a DLC exit, same as the Western canyon. It will open when you get the DLC (in all probability)

Where can I find this western canyon?

erm... go out of Primm, and travel West. You will need to go around the NCR camp. It's up in the mountains. (best to leave Primm via the south, then go straight west past the drive-in) More stuff up in those mountains too

It's actually called Canyon Wreckage, I think.

The northern passage is up in the mountains to the north of prim, there is a grave beside the entrance and inside the grave there is a nice prize but you have to have a shovel to get it out.

North of Primm? Is that your closest reference point? Heh, they're on the North border of the map, above Vegas.