A river runs through it. Many State lines are determined by the wandering of a large river, and that's what happened here. Kansas City Missouri is close to the the landing at Westport, MO which was the jumping off point for the wagon trains heading west.
Some wagon trains would cross the river during the late afternoon, and staying close to the river provided water and the protection of many people.
Starting out to cross half the United States, knowing how far it was between civilized points where they could trade and restock food or buy horses, etc., called for courage that a great deal of people of today simply don't have.
I ws born in Missouri, and have been a fan of the Tigers for a long time. Recently, however, they decided to take their college out of the Big 12 Sports Conference and jump to the South East Sports Conference (SEC), and I am angry with them.