Quashing worries that job growth was flagging, the government on Friday reported that employers increased payrolls by 287,000 in June. The arresting surge comes as Republicans and Democrats fine-tune the economic messages they plan to deliver at their conventions later this month.

The official unemployment rate did rise to 4.9 percent, from 4.7 percent, but that was largely because more Americans rejoined the workforce. And average hourly earnings increased again, continuing a pattern of rising wages that brought the yearly gain to 2.6 percent.

“Wow, this one takes my breath away,’’ said Diane Swonk, an independent economist in Chicago.

An unexpectedly grim employment report in May, combined with Britain’s vote to leave the European Union, had fanned concerns that the American economy was in danger of stalling. During its meeting last month, the Federal Reserve decided to postpone increasing its benchmark interest rate.

Every monthly jobs report provides only a fleeting and incomplete picture, and a strike by more than 35,000 Verizon workers had artificially held down May’s totals. Concerns persist about the vitality of the economic recovery.

But Friday’s report, with the largest single monthly job expansion since October 2015, helped whisk away some of the cloudiest forecasts. The three-month average of monthly gains rose to 147,000, after taking into account the Labor Department’s revised estimates that showed 6,000 fewer jobs were created in April and May than previously reported.

“This report should ease any fears that a persistent slowdown or recession is coming soon in the U.S.,’’ said Dean Maki, chief economist at Point72 Asset Management. “The service sector is where the real strength is, with 256,000 hires. But the gains were widespread across sectors.’’

Maki pointed out that the vigorous report was in line with several other encouraging signs. New claims for unemployment benefits have stayed at rock-bottom levels. Consumer spending is strong. The manufacturing and service industry indexes have jumped. And the number of unfilled jobs, 5.8 million in April, is at a record since the survey began.