The number of available jobs in the U.S. exceeded the number of job seekers by more than 650,000 in July—a gap that has been growing—in a sign of an increasingly tight labor market that is altering how employers find workers.

The number of available jobs in the U.S. rose by about 117,000 to a seasonally adjusted 6.94 million in July, the Labor Department said Tuesday. That is the highest level on record back to 2000, exceeding the prior peak set in April. It also exceeds the 6.28 million Americans who were unemployed during the month, meaning they were without work but actively seeking a job.

Such a gap never occurred before March in the records going back to 2000, but a gap has occurred in every month through the August report.

“The supply of workers is very limited and the demand for labor is expanding,” said Becky Frankiewicz, president of staffing firm ManpowerGroup North America. “Employers have to be more open to let people in they might not have before.”

The tight labor market—shown by an unemployment rate holding near a 17-year low—is shifting more power to workers. And increasingly they are willing to quit their jobs. In July, 3.58 million workers voluntarily left their jobs, the highest level on record, the Labor Department said.