Based on the excerpt, the statement that can be inferred about the effect the Louisiana Purchase would have on the United States is: Because of the purchase of the territory, Americans could now legally start settling regions in the West.
The excerpt mentions that the purchase "doubled the size of the country and paved the way for westward expansion," which suggests that the acquisition of this territory would enable settlement in the West. The other statements do not align as closely with the information presented in the excerpt.