I was looking at pictures of covered wagons used for the trail. They ranged from fancy to they put this together in a hurry.
The famous wagon is the Conestoga Wagon. They were first built in Lancaster Pennsylvania. These were called Prairie Schooners. The white covering looked a bit like sailing ships. Later on, Prairie Schooner was used for any covered wagon.
Other wagons were made in the form of the Conestoga Wagon, but were different in some ways.
Conestoga Wagons were very strong, heavy and large. They could carry about 7 tons, that’s 14,00 pounds.
The problem was that the wagons were too large to go over the Rocky Mountains. That’s how other typed of covered wagons started to be made. Even farm wagons were made into covered wagons.
The pictures are from Wikipedia Commons, unless I put a different label.

The Conestoga Wagon.

From Library of Congress

By, National Park Service

By, Podruznik, English Wikipedia

The ends of the covered hoops were slanted out from the others on the Conestoga Wagons. This prevented rain from getting into the wagon.
This drawing of a basic frame of a model covered wagon is from the National Park Service.

The wagon box was made from hardwood. This kind of wood wouldn’t swell when wet and wouldn’t shrink when the weather was hot and dry. Tar could be used to seal the wood.
They didn’t paint the woo because paint would dry out the wood.
The wagon box had to be waterproof when they crossed rivers. A well made wagon box would float in water deeper that the bottom of the wagon.
On the Conestoga Wagon, the floor of the wagon box sloped toward the middle so things wouldn’t roll and hit the sides of the box.
The hoops for the cover were made of wood that was soaked in water and then bent into shape. They had to fasten the hoops very well. If a hoop came loose, it could tear the cover.

The covers could be made of sailcloth. They also used other types of cloth and used linseed oil or beeswax to waterproof the cover.
The covers were fastened tightly to the bottom of the hoops or the wagon box. If a flap of cloth was picked up by the wind, It could tear off the entire cover.

The wheels were made of wood. They had iron rings on the outside to make them durable. The wheels could be put in a river to prevent the wood from shrinking. If the wood shrank enough, the iron rings would fall off.
There were brakes on the wheels and a brake lever to operate them. I am not sure the breaks were helpful on mountains. It was a lot of weight to stop uphill or downhill.

I read that the average wight of supplies that people put in the wagons was about 1,000 pounds.

More pictures of different kinds of covered wagons.

Photographer unknown

By, Gary Halvoson, Oregon State Archives

A modified covered wagon, not used on the trail. By, Russel Lee, 1903-1986, Library of Congress

The last picture is of a covered wagons during a reenactment of a trip on the Oregon Trail  by, National Park Service.