Answer: The Mexican Cession
Explanation: If we are measuring this impact by land area, the mexican cession definitely had the biggest impact, since it was the first land acquisition that connected the US to the Pacific and truly accomplished manifest destiny.
50 States in the United States
It was a direct result of the First Indochina War (1946–1954) between France, which claimed Vietnam as a colony, and the communist forces then known as Viet Minh.
