WASHINGTON — U.S. employers posted slightly more openings in June than in May, resulting in more available jobs than unemployed people for the third straight month.

The Labor Department said Tuesday that job openings barely increased, rising 3,000 to 6.66 million. That’s more than the 6.56 million people who were searching for work in June. It’s also close to April’s figure of 6.8 million, a record high. Overall hiring slipped to 5.65 million from 5.75 million, and the number of people quitting their jobs declined slightly to 3.4 million from nearly 3.5 million in May.

The figures reflect a robust job market. The unemployed typically outnumber job openings, but that reversed this spring amid strong demand from employers. Businesses are optimistic about the outlook and stepping up hiring in anticipation of future growth. The economy expanded at a 4.1 percent annual rate in the April-June quarter, the fastest pace in four years.

Last week, the government said that employers added 157,000 jobs in July and the unemployment rate fell to 3.9 percent, near an 18-year low. That figure represents a net gain, while Tuesday’s report, known as the Job Openings and Labor Turnover survey, or JOLTS, measures total hiring before quits, layoffs and retirements.

The proportion of workers quitting their jobs is at the highest level in nearly 13 years.

Average hourly wages rose 2.7 percent in July from a year earlier, the Labor Department said last week. Yet rising inflation has offset that gain.