What was the largest contiguous Empire in history

What is the name for the main idea behind the settling of western lands by americans in the early-1800s?

What is the main reason the united states removed the taliban from power shortly after the september 11 2001 attacks ?

What did this mean for dred scott? a.scott was not a citizen of the united states. b.scott was the property of the federal government. c.scott had no right to sue for his freedom in court. d.scott was considered the property of the slaveholding family.