How long has there been a "Poet Laureate" for the United States?

from Writer's Almanac (American Public Media, Garrison Keillor):
On Dec. 20 in 1985, President Ronald Reagan signed a bill establishing an official poet laureate for the United States. As the Library of Congress explains, the poet laureate is to serve as “the nation’s official lightning rod for the poetic impulse of Americans” and is charged with the task of seeking to raise a greater national appreciation for the reading and writing of poetry.
Each poet laureate is appointed by the Librarian of Congress and the position has been held by such notable writers as Billy Collins, Louise Glück, and Charles Simic. Juan Felipe Herrera is the most recent poet to hold this distinguished post.