Sentence:  This delightful tropical fruit has become well-known in the past thirty years because modern transportation methods have made it possible to ship avocado anywhere in the <WSD>United</WSD> States . 
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