In the U.S. Constitution, “United States of America” is a plural noun, as in:
No Title of Nobility shall be granted by the United States: And no Person holding any Office of Profit or Trust under them, shall, without the Consent of the Congress, accept of any present, Emolument, Office, or Title, of any kind whatever, from any King, Prince, or foreign State. . . .Today we refer to the “United States” as a singular entity. And lots of people trace that change to the U.S. Civil War of the 1860s. That idea got a big boost in 1988 when historian James McPherson write in Battle Cry of Freedom:
Treason against the United States, shall consist only in levying War against them, or in adhering to their Enemies, giving them Aid and Comfort.
Before 1861 the two words ‘United States’ were rendered as a plural noun: “the United States are a republic.” The war marked a transition of the United States to a singular noun.Two years later, historian Shelby Foote gave that statement an even bigger boost by echoing it in Ken Burns’s Civil War television series and accompanying book.
In 2005 Ben Zimmer at Language Log dug back into the record, finding expressions of the idea as early as the 24 Apr 1887 Washington Post:
There was a time a few years ago when the United States was spoken of in the plural number. Men said “the United States are” — “the United States have” — “the United States were.” But the war changed all that. . . . The surrender of Mr. Davis and Gen. Lee meant a transition from the plural to the singular.In 1902 the U.S. House of Representatives’s Committee on Revision of the Laws decided that henceforth Congress should refer to “the United States” as singular.
In 2009 (after Language Log got a new design), Marc Liberman started exploring the idea through historic newspapers, Presidential speeches, and Supreme Court decisions. He saw usage evolve but didn’t find a clear-cut change around the Civil War.
I decided to use the less sophisticated toll of the Google Books Ngram Viewer, looking for “United States is/was/are/were” across its database of publications from 1780 to 2000.
That method brings up a lot of false hits because it doesn’t distinguish between phrases in which “United States” is the actual subject of a sentence and phrases in which it’s helping to modify the subject, such as “The laws of the United States are based on British traditions” or “The President of the United States is an idiot.” But if those other constructions appear at a steady rate, then the comparison is still meaningful.
Here’s the graph that the Ngram Viewer produced for me.
Also interesting, the peaks in appearances of any form of “United States is/was/are/were” within the corpus of publications coincide with U.S. entry into the two World Wars and the Vietnam War.