1843: The first major wagon train sets out on the Oregon Trail

 

(Wikipedia) ... In what was dubbed "The Great Migration of 1843" or the "Wagon Train of 1843", an estimated 700 to 1,000 emigrants left for Oregon.
They were led initially by John Gantt, a former U.S. Army Captain and fur trader who was contracted to guide the train to Fort Hall for $1 per person. The winter before, Marcus Whitman had made a brutal mid-winter trip from Oregon to St. Louis to appeal a decision by his mission backers to abandon several of the Oregon missions. He joined the wagon train at the Platte River for the return trip.
When the pioneers were told at Fort Hall by agents from the Hudson's Bay Company that they should abandon their wagons there and use pack animals the rest of the way, Whitman disagreed and volunteered to lead the wagons to Oregon. He believed the wagon trains were large enough that they could build whatever road improvements they needed to make the trip with their wagons. Continued