The Meghri-Nordooz border crossing is the only border crossing point between Armenia and Iran. Crossing on foot between the checkpoints is possible (december 2011). Best way to leave the border checkpoint is probably to take a taxi to the actual town of Meghri and then walk out of it (it's not so far). Once you're out, it's pretty easy to hitchhike as there is only one road going until Goris (that will take you a while as it is a mountain pass). The traffic volume is quite low, and a lot of it is local traffic or taxi's. You might have to wait a while to hitch across if you've arrived without a lift. You might be able to sleep in either terminal if you ask the guards nicely enough. Keep in mind also that the guards on the Armenian side actually aren't Armenian but Russian soldiers.
Meghri-Nordooz border crossing
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|Countries:||Iran | Armenia|
If you want to reach Tabriz after crossing toward Iran, hitch the main road toward the east, this is the way taken by most car going there. i.e. They don't take the small direct mountain roads going to the south.
Telling you will do auto stop to the Iranian border guard seems not to be an issue.