When did “The United States” become a singular noun?S

"There was a time a few years ago when the United States was spoken of in the plural number," reads an article published April 24th, 1887, in The Washington Post. "Men said 'the United States are' — 'the United States have' — 'the United States were.' But the war changed all that."

The quote continues (emphasis added):

Along the line of fire from the Chesapeake to Sabine Pass was settled forever the question of grammar. Not Wells, or Green, or Lindley Murray decided it, but the sabers of Sheridan, the muskets of Sherman, the artillery of Grant. ... The surrender of Mr. Davis and Gen. Lee meant a transition from the plural to the singular.

The passage got redditor LeftHandedMasterRace (who goes by Kyle IRL) thinking. "I found [the] idea fascinating, and wanted to see if the plural-to-singular shift was actually reflected in linguistic data (because I'm the sort of person who does that)" he tells io9. So he turned to Google's N-gram Viewer, a tool that lets anyone with an internet connection scour the Google Books library for words and phrases and track how the frequency of those words changes over time. Kyle used the Viewer to chart the appearance of "The United States is" and "The United States are" between 1760 and 2008. Here's what he found:

When did “The United States” become a singular noun?S

"It seems that the old saying was correct in that there was little use of the singular United States prior to the 1860s," Kyle writes on the reddit post where he first shared his discovery last night. "However, it took until well into the 20th century for the plural convention to die out entirely."

A few hours after Kyle posted his initial data, redditor pqn chimed in with a graph that depicts the frequency of each phrase in relative percentages, making the transition from singular- to plural-usage even more noticeable:

When did “The United States” become a singular noun?S

Kyle tells io9 he was surprised at the accuracy of the WaPo quote. "I was suspecting it to be more poetic than actually based in real observation," he says. Interestingly, a search of Google's fiction-only corpus reveals an even more dramatic shift to singular-noun usage:

When did “The United States” become a singular noun?S

Kyle explains:

One of the limitations of searching old books to find evidence of linguistic change is that literature does not necessarily reflect the language being spoken in casual, day-to-day conversation. So even though it took until two decades after the Civil War for "The United States is" to become the norm in literature, the change may have been much quicker among the general public. I tried searching only fiction on the grounds that fiction might be more representative of casual speech. And the difference seems to be fairly dramatic! The end of the Civil War sees a steep decline in the use of the plural USA coupled with the sudden emergence of the singular. It took another few decades to figure things out decisively, but it seems the old saying was on to something.

Not surprisingly, Kyle's post has spawned some incredibly interesting discussion over on reddit, including a slew of hypotheses for the peaks and valleys observable throughout the data, and even more analysis from Kyle. All in all, some really great internet sleuthing and a fascinating mashup of history, linguistics and data-analysis – a compelling addition to the longtime discussion over the philological underpinnings of these/this United States.