Sentence:  During the trip Selkirk decided that the route through Illinois territory to Indiana and the eastern <WSD>United</WSD> States was the best route for goods from England to reach Red River and that the United States was a better source of supply for many goods than either Canada or England . 
Meaning of the word marked with <WSD> tags:  North American republic containing 50 states - 48 conterminous states in North America plus Alaska in northwest North America and the Hawaiian Islands in the Pacific Ocean; achieved independence in 1776