Which river formed the western boundary of the United States after the American Revolution?

Which river formed the western boundary of the United States after the American Revolution?

• A. Mississippi River
• B. Ohio River
• C. Colorado River
• D. Rio Grande

Answer: (A)

The main idea is that a clear, natural dividing line was established as the United States’ western border after independence. The Treaty of Paris in 1783 set the western boundary as the Mississippi River, so American territory extended east of the river while lands to the west remained under other powers. The river’s size and course made it a practical, identifiable border between newly formed U.S. lands and nearby regions controlled by Spain and other powers at the time. The other rivers don’t fit this enduring boundary: the Ohio River was important in early boundary talks, but it did not define the entire western edge of the United States; the Colorado River is far to the southwest and not part of the postwar boundary; the Rio Grande became a boundary with Mexico much later, after U.S. territorial expansion in the 19th century.

The main idea is that a clear, natural dividing line was established as the United States’ western border after independence. The Treaty of Paris in 1783 set the western boundary as the Mississippi River, so American territory extended east of the river while lands to the west remained under other powers. The river’s size and course made it a practical, identifiable border between newly formed U.S. lands and nearby regions controlled by Spain and other powers at the time. The other rivers don’t fit this enduring boundary: the Ohio River was important in early boundary talks, but it did not define the entire western edge of the United States; the Colorado River is far to the southwest and not part of the postwar boundary; the Rio Grande became a boundary with Mexico much later, after U.S. territorial expansion in the 19th century.