Closest to me (in Austin, TX) is the massive Carrizozo Lava Flow in NM. I've actually been there via the Valley of Fires State Park. It's an amazing place, and

Closest to me (in Austin, TX) is the massive Carrizozo Lava Flow in NM. I've actually been there via the Valley of Fires State Park. It's an amazing place, and seems to be usually empty- definitely worth a visit if you're in the area!