Plenty of events to choose from here: https://en.wikipedia.org/wiki/1971 Highlights: - "A new stock market index called the Nasdaq Composite debuts." - "Starbucks, a major coffeehouse and outlet in worldwide, is founded in the U.S. State of Washington." - "The U.S. ends its trade embargo of China." - "President Richard Nixon declares the U.S. War on Drugs." - "Southwest Airlines, a low-cost carrier, begins its first…
When analyzing wage stagnation in a finer detail: Going off the gold standard caused a rise in the stock market. Also, we have regulated food prices in the US, so the current metric we use to measure inflation isn't strongly correlated to a living wage. Meanwhile, people who are invested in the stock market and rental properties, aka the upper 10%, have seen a large boom in wealth. (Not just the upper 1% have had a rise in wealth.) Unless we have any other ideas that is being overlooked here, it does in fact look like going off the gold standard started this trend, and has only been amplified by trade and tech later on.
Could it be possible that unionized workers started shrinking in 1971? They're commonly cited by historians as a key element in the rise of working class wages, so it would be a good place to check to see if there is a correlation there.