At the end of one winter during the late 1860s, Pa decides that Wisconsin, where the Ingalls family lives, is getting too crowded for him, so he moves his family to Kansas, which is less settled. He has heard that the US government will soon be displacing the Indigenous Americans from their territory in Kansas and opening up the land to white settlers, and he is determined to get an early claim on good farming land. 

The family sells their house and makes the trip in a covered wagon, leaving early one morning and crossing the frozen Mississippi River at the town of Pepin, on the Wisconsin-Minnesota border. Once on the Minnesota side, the family spends the first night at a deserted cabin used by travelers. In the night, Laura hears the ice on the river breaking up, realizing that the family crossed it just in time. 

From Minnesota, the family goes south through Iowa and Missouri, then turns west to reach the plains of Kansas. They must cross many streams and rivers as they travel, some of which are flooded from the winter’s snowmelt. They wait until the water drops down and buy new horses to pull their wagon while they wait.