Here in Hawaii County (Big Island), its legal to ride in the bed of a pick up truck on a highway, although if you are inside the truck without a seat beat on, they will ticket you in an instant. It makes no sense. I guess its the way it was back in the day in rural Hawaii.
What’s the law in your state or county?
No seatbelt, no ride, at least in my state. Subaru used to sell a little pickup with a seat in the bask, and seat belts. That was okay here.
It’s not illegal in Arizona, however, police are required to issue a warning (not a citation) if anyone in the back is under 18. It is not a primary stopping offense, though, only secondary to an offense for which you can be pulled over. Not wearing a seatbelt is a secondary offense, but in certain counties you can be pulled over for holding a cellphone while driving.
You might find this useful: http://drivinglaws.aaa.com/tag/seat-belts/
Though:
They say Hawaii is semi-restrictive, so I can’t account for its current veracity.
Here, legal if 18. Under 18 only in agriculture, ranching, or parades, or with camper shell. Fine is surprisingly low, $35-100 (driver gets the ticket).
Texas: Legal to ride in the bed as long as it’s under 35MPH. (No highway travel obviously)
Nope, that don’t stop the idiots though.
39:4-69. Riding on part not intended for passengers prohibited
No person shall ride on, and no operator shall knowingly allow a person to ride on a street car or vehicle, or on a portion thereof not designed or intended for the conveyance of passengers. This section shall not apply to an employee engaged in the necessary discharge of a duty.
The above is the MV statute in New Jersey. That last sentence covers sanitation workers hanging on to the back of garbage trucks. It’s also not a statute that is enforceable on private property so if a farmer wants someone to ride in the back it’s not covered.
Was common in the old days and I’d done it a number of times even when the driver got pulled over for some other offense cop didn’t care about riding in bed.
However definitely illegal in California at the present.
Except it’s not correct, at least for my state anyway.
Riding in the cargo area of a pick up in Wisconsin IS legal if the passenger is over 16 years of age.
I’m anticipating a seatbelt law for motorcycles any day now. 
I rode in the bed of a pickup many, many times growing up in a rural area. We only rode on gravel roads going under 20 mph. My uncle’s old truck wasn’t capable of interstate speeds. LOL They used my aunt’s car for any trips.
I’m not sure if it’s legal anymore in my state. I’d assume the seatbelt laws included the backs of pickups.
Which is why I put a caveat in the part you specifically removed from the quote, ya curd munching, brandy swilling pseudo-Minnesotan.
California ruins anything fun, but the only exception is allowing lane splitting.
Per the link in post #4, in Arkansas passengers inside the vehicle must wear seat belts and violation is a standard offense. Riding in the open back of a pickup is prohibited except for employees on duty.
Virginia prohibits riders under 16 in the back of a pickup truck, except in parades or to cross a highway between fields.
One of the great joys of childhood, justifiably prohibited these days in most places.
[tangent]
When I was in high school, my brother and I went to Detroit to see Roger Waters in concert. After the concert my car wouldn’t start, so we begged his friends to take us home in their pickup truck. They were already 4 (two couples), so we ended up as 6 people squeezed into the cab of a mini pickup in the cold winter night.
We made it about two blocks before we watched a Detroit city cop count us off on his fingers at a traffic light. He pulled us over.
The cop said he would have let 4 in the cab slide, but 6 was too much. He ticketed the driver and said we could go home only if my brother and I rode in the bed…in winter, on the freeway, in Michigan.
I imagine these days the story would have gone a different way, likely involving my brother and I being stuck in Detroit and calling our mom.
[/tangent]
It is not legal in New Jersey. I haven’t seen it here since I was in high school except for a landscaper’s truck sometime in this summer.
I heard of a case quite a few years ago where someone was coming back from the cottage, about 30 miles into town. they had an inflatable boat inflated(!) in the pickup bed, and a teenage girl decided she would ride home sitting in the boat. Once they got out on the highway, to paraphrase Tennyson, “out flew the boat and floated wide…” The girl hit the ground at about 70mph and died.
AFAIK it is illegal to ride in vehicle without your individual seatbelt, done up properly, anywhere in Canada. You get a ticket - unless you’re under 18, the driver gets the ticket.
Table at: http://www.iihs.org/iihs/topics/laws/cargoareas
http://www.attorneys.com/traffic-tickets-violations/riding-in-the-back-of-a-pickup
Legal in 20 States
Twenty states have no laws prohibiting riders in the back of pickup trucks. Not surprisingly, most of these states contain substantial rural areas where pickup trucks are needed for work uses. The states are Alabama, Alaska, Arizona, Delaware, Idaho, Illinois, Indiana, Iowa, Kentucky, Minnesota, Mississippi, Montana, New Hampshire, North Dakota, Oklahoma, South Dakota, Vermont, Washington, West Virginia, and Wyoming.
In Washington, you can only ride in the bed of the pickup if all seatbelts in the cab are being used. Idaho on the other hand allows anyone to ride in the bed regardless of seatbelt use in the cab.
In Nevada (where I got my US license, hence why I know, as it came up on my written test) it is only legal if you live in a county with less than 100,000 people (interestingly also the threshold for being able to have a legal brothel in a county)
Link? NRS 484b says nothing about that; the only mention of that population is with regards to speed limit fines.