Which territorial acquisition - excluding the original United States- - added the greatest number of states to the nation?

Gadsden Purchase

Louisiana Purchase

Mexican Cession

Oregon Territory

The terriotrial acquisition that added the greatest number of states to the nation was: The Lousiana Purchase, which was the acquisition of the Lousiana territory from France in 1803. The Lousiana territory included lands from 15 present U. S. states and 2 Canadian provinces. This territory contained land that forms Arkansas, Missouri, Iowa, Oklahoma, Kansas and Nebraska, and portions of Minnesota, North Dakota, South Dakota, New Mexico, Texas, Montana, Wyoming, Colorado and Lousiana.