US Inflation Quickens to 9.1%, Amping Up Fed Pressure to Go Big

US inflation roared again to a fresh four-decade high last month, likely strengthening the Federal Reserve’s resolve to aggressively raise interest rates that risks upending the economic expansion.

The consumer price index rose 9.1% from a year earlier in a broad-based advance, the largest gain since the end of 1981, Labor Department data showed Wednesday. The widely followed inflation gauge increased 1.3% from a month earlier, the most since 2005, reflecting higher gasoline, shelter and food costs.

Economists projected a 1.1% rise from May and an 8.8% year-over-year increase, based...