The pioneers would sometimes make a wax paste and water proof their wagons to float them across while making the animals swim across. Also, sometimes there would be Native Americans that would ferry them across for trade or money. If the rivers were very deep, they would make the animals swim and build a large flat boat called a scow to float themselves and their wagon(s) across.
pioneers found high spots in the river to cross with their wagon
They had to be very careful. Most of the time they could follow the river and pick a low spot if they needed to cross.
Most Mormon pioneers crossed the Mississippi River in early 1846.
Potomac River
The Columbia River is the major river in Washington.
Columbia river
The Oregon Trail crossed several significant bodies of water, including the Missouri River, which marked the starting point, and the Platte River, which provided a vital water source for travelers. Additionally, the trail crossed the Snake River and the Columbia River as pioneers made their way into the Oregon Territory. Other smaller rivers and streams also presented challenges and opportunities for water supply along the route.
They crossed at low spots, took a barge down where they paid a man to cross, or tried to cross and got flooded out.
Columbia River
The Columbia River originates in British Columbia
The Columbia River borders most of the length between Washington & Oregon.
The Arkansas River.