The first $1 Federal Reserve notes were issued in 1963. The design, featuring George Washington on the face and the Great Seal on the back, has not changed.
The first $1 notes (called United States Notes or "Legal Tenders") were issued by the federal government in 1862 and featured a portrait of Secretary of the Treasury Salmon P. Chase (1861-1864).
The first use of George Washington's portrait on the $1 note was on Series 1869 United States Notes.
If you had 10 billion $1 notes and spent one every second of every day, it would require 317 years for you to go broke.
Because the $1 note is infrequently counterfeited, the government has no plans to redesign this note. In addition, there is a recurring provision in Section 116 of the annual Financial Services and General Government Appropriations Act that prohibits the redesign of the $1 note.
All U.S. currency remains legal tender, regardless of when it was issued.