Final answer:
The Northern region's harsh climate with cold continental and arctic climates has most limited the movement of people in North America due to its long winters and poor soils, making it the least densely populated area.
Step-by-step explanation:
The physical feature that has most limited the movement of people living in North America is the brutally cold and inhospitable climate of the Northern regions, which includes the boreal forests of the upper Great Lakes region, the Canadian Shield, and the territory stretching to the Arctic Circle. This region is characterized by cold continental and arctic climates, long winters, and arctic air masses. The frigid temperatures, short growing seasons, and poor soils make it the least densely populated area in North America, imposing significant limitations on human settlement and population movement. Most inhabitants live in the forested areas rather than in the frozen Arctic. In comparison, areas with milder climates closer to the US border have higher population densities and better conditions for agriculture, prompting more widespread human settlement.