Final answer:
The President and Vice President are the only offices in the U.S. elected on a nationwide basis, with other national figures like representatives and senators representing specific districts and states.
Step-by-step explanation:
The only offices elected on a nationwide basis in the U.S. are the President and Vice President. While there are over 500,000 elected positions across various levels of government in the United States, the President and Vice President are the only national offices that are elected by the entire voting population through a process involving the Electoral College. The House of Representatives and Senate are part of the national governmental structure but their members are elected by constituents within their respective congressional districts and states, not on a nationwide basis.