Q: “When push comes to shove” does not come up in my QPB Encyclopedia of Word and Phrase Origins. What do you have to say about the evolution of this phrase?
A: The expression “when (or if) push comes to shove” originated in 19th-century African-American usage, according to the Oxford English Dictionary.
The OED labels it colloquial—more likely to be found in speech than in formal writing—and says it means “when action must back up words” or “if or when one must commit oneself to an action or decision.”
People generally talk about a problem before finally doing something about it. So think of talking as the “push” and acting as the “shove.”
The expression wasn’t recorded until the 1890s, according to OED citations, but no doubt it was used conversationally for years before it ever showed up in print.
Oxford gives a hint of the reasoning behind the saying in this 1873 citation from Thomas De Witt Talmage, writing in the United Methodist Free Churches’ Magazine:
“The proposed improvement is about to fail, when Push comes up behind it and gives it a shove, and Pull goes in front and lays into the traces; and, lo! the enterprise advances, the goal is reached!”
A version of the expression that used “pinch” instead of “push” appeared in a February 1897 issue of a Georgia newspaper, the Macon Telegraph:
“But, ‘if pinch comes to shove’ as old Sol … was wont to say, will these gentlemen put on the habilaments of war and prove ‘more than a match’ for British ironclads or Spanish machetes?”
The same newspaper printed the more familiar version in February 1898: “When ‘push comes to shove’ will editors of the Yellow Kid organs enlist?”
A prominent African-American newspaper, the Chicago Defender, printed the expression in 1924 (“what Uncle Sam can do if push comes to shove”), and in a 1948 piece by the poet Langston Hughes:
“Civilizations, like clocks, have a way of running down—only to be replaced by new versions. One can always buy another clock, or even tell time by the sun, if push comes to shove.”
While the expression originated in the United States, it’s not unknown elsewhere. The OED’s citations include examples from Canada and Scotland:
“If push comes to shove, make good the threat.” (From an Alberta newspaper, the Calgary Herald, 1970.)
“I can see you taking legal advice on your position so that you’ll know what to do if push comes to shove, but you’ll try to work things out first.” (From the Sunday Post, Glasgow, 1997.)
from Grammarphobia http://www.grammarphobia.com/blog/2016/02/when-push-comes-to-shove.html