Calhoun proposed that Congress should not exclude slavery from territories but let each state choose for itself whether it would allow slaves within its borders.

He opposed Tennessee Congressman Andrew Johnson's Homestead Bill, fearing it would create more territories that excluded slavery.

In the Territory of Nebraska the fight to exclude slavery from within the territorial boundaries spread from the Senate to the press and to the pulpit.

A crucial moment came when Lincoln asked Douglas if the people of a territory could exclude slavery before the territory became a state.

Nebraska residents, many of them migrants from the Northern United States, chose to exclude slavery from their territory.

Alabama delegates to the Democratic convention were to oppose any candidate supporting either the Proviso or Popular Sovereignty (which allowed territories to exclude slavery at any point)

The ordinance defined the boundaries of the future states, excluded slavery, and required that 60,000 inhabitants be present for statehood.

Following the U.S. victory over Mexico, Northerners attempted to exclude slavery from conquered territories in the Wilmot Proviso; it never passed.

In 1848, he introduced a resolution that recommended New Mexico and California have territorial governments which excluded slavery.

For example, in the Lincoln-Douglas debates Lincoln asked Douglas whether the people in the territories could, in any lawful way, exclude slavery before the formation of a state constitution.