NEW YORK (AP) — St. Patrick's Day celebrations across the country are back after a two-year hiatus, including the nation's largest in New York City, in a sign of growing hope that the worst of the coronavirus pandemic may be over.

The holiday served as a key marker in the outbreak's progression, with parades celebrating Irish heritage among the first big public events to be called off in 2020. An ominous acceleration in infections quickly cascaded into broad shutdowns.

The full-fledged return of New York's parade on Thursday coincided with the city's wider reopening. Major mask and vaccination...