Data: U.S. Census Bureau Vintage 2025 population estimates; Chart: Russell Contreras/Axios America has a missing-middle problem — and this one is demographic. Why it matters: The shrinking 45-64 population could leave fewer experienced adults to run institutions, mentor younger workers and care for the fast-growing population behind them. This is the Gen X-ish squeeze: The age group includes most of Generation X, plus younger baby boomers. It also overlaps with the "sandwich generation" years,