-Bronco II- yep, I had one, about all I want to say about that
I have a copy of the original Off Road Magazine issue, which has their overland debut in Turtle I, their Land Rover Series II.
I'm surprised this one hasn't been brought up yet. Born of war and in production to the civilian market from 1946 to 1971 (the last 3 years were for export production), the Dodge Power Wagon has served on nearly every continent and a variety of no-kidding expeditions.
Tough as nails and easily maintained and repaired it was marketed by Dodge as the "farm truck." Refurbished as a retromod it's pretty sweet with modern running gear, like the one I took a picture of in Wyoming in 2011, above.
In its original form it would be a little tough for extended travel these days but I think you can make a case of it being one of the greatest overland vehicle ever sold new in the US.
Strictly by the numbers...the most popular overland vehicle actually used, built and sold in the US by average families is likely the Dodge Caravan and its corporate relatives. Add up the collective adventures the millions of Caravans have accumulated over the years and it's a damn tough act to follow.
Ha Ha Ha, funny you bring up the Caravan as an overlander. I spent four years, between 2000 and 2004, exploring every nook and crannie of Eastern and Western Europe in a 1997 US spec Grand Caravan. It was a roomy, trouble free, sleep in the back rig with a healthy appetite for front brake pads. Many good times and many bucket list experiences/destinations in the old Dodge GC.