Sentence:  During the trip Selkirk decided that the route through Illinois territory to Indiana and the eastern United States was the best route for goods from England to reach Red River and that the <WSD>United</WSD> 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