After a steep rise following the financial crisis, U.S. retail jobs have been plummeting since the start of the year.

Why this matters: The likely irreversible plunge in these relatively low-wage jobs — $18-an-hour employment for teens, adults, immigrants and senior citizens for generations — primarily affects the working class people whose shrinking opportunities have underpinned populist politics in the U.S. and abroad. And the jobs being created in their stead, in online warehouses for companies like Amazon, are too few to soak up those displaced.

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Data: Bureau of Labor Statistics; Chart: Lazaro Gamio / Axios

Our thought bubble: Until now, retail workers — unlike the car-making and coal-mining industries — have made little political splash. Look for that to change.

The numbers: U.S. retail jobs (mainly cashiers and sales people) plummeted by about 60,000 in the first three months of the year, to about 15.85 million, according to preliminary data from the Bureau of Labor Statistics.

Reality check: That decline is more than the 53,000 people employed in all aspects of coal mining, including executives and administrative staff, an industry on which President Trump has been fixated.

What they're saying: "The backdrop is that there have been significant layoffs in major retail including department stores," said Mark Muro, of the Brookings Institution. "The department store platform seems to be falling apart."

Why now? The dramatic consumer rush to online shopping. This is reflected in a rise in the number of jobs in Amazon-type jobs, which pay more — an average of about $25 an hour, according to the BLS. But Amazon and the other online merchandizers are rapidly automating, so the number of jobs rose only by 9,300 in the first three months of the year, to about 555,700.