“The probability of ending where you start has gone up, and the probability of moving up from where you start has gone down,” Carr said. For instance, the chance that someone starting in the bottom 10 percent would move above the 40th percentile decreased by 16 percent. The chance that someone starting in the middle of the earnings distribution would reach one of the top two earnings deciles decreased by 20 percent. Yet people who started in the seventh decile are 12 percent more likely to end up in the fifth or sixth decile—a drop in earnings—than they used to be.

Overall, the probability of someone starting and ending their career in the same decile has gone up for every income rank. “For whatever reason, there was a path upward in the earnings distribution that has been blocked for some people, or is not as steep as it used to be,” Carr said.

Carr and Wiemers’ findings highlight a defining aspect of being middle class today, says Elisabeth Jacobs, the senior director for policy and academic programs at the Washington Center for Equitable Growth, the left-leaning think tank that published Carr and Wiemers’ paper. “If you’re in the middle, you’re stuck in the middle, which means there’s less space for others to move into the middle,” she said. “That suggests there’s just a whole bunch of insecurity going on in terms of what it means to be a worker. You can’t educate your way up.”