That figure accounts for both public and private payers, but the government-run programs are the largest drivers of the growth, with Medicare by far the biggest of the bunch. Over the next decade, Medicare spending is expected to rise by 7.4 percent each year, while spending on Medicaid, the joint federal-state health program for the poor and disabled, is set to rise by 5.5 percent annually. Spending on private health insurance is projected to rise as well—but at 4.7 percent annually, the increase won’t be as fast. Increased spending on Medicare (and to a lesser extent Medicaid) is the main factor.

That increase is primarily a result of demographic change as more seniors enter the program. More enrollees means higher costs. But Medicare won’t just cover more people. It will increase the average amount it spends on each person—and that increase will be larger than the commensurate increase in private health care spending. Supporters of Medicare for All sometimes argue that although the government cost would be significantly higher, total national health spending would decrease. That only holds under the improbable assumption that health care providers could absorb large reimbursement cuts without service disruption. In any case, these estimates suggest the weakness of attempting to control overall spending growth through Medicare, which is expected to substantially outpace private insurance spending growth.