U.S. employers hired significantly more people in April, making it the strongest month for hiring since June 2015, according to the LinkedIn Workforce Report.

The report, released Wednesday, said seasonally adjusted hiring in April was 3.4 percent higher than in March, and hiring across the U.S. was 16.7 percent higher than a year ago.

The LinkedIn report said seasonally adjusted hiring was mainly fueled by three industries: manufacturing and industrial, which was up 0.5 percent, aerospace, automotive and transport, up 1.3 percent, and software, up 8.5 percent.

"Keeps happening every month. We're seeing these massive year-over-year increases," Dan Roth, LinkedIn editor-in-chief, said on "Squawk Box."

The source of LinkedIn's data includes its 138 million user profiles in the U.S., 20,000 company profiles and 3 million monthly job postings.

Seattle and Denver continued to gain the most workers. However, Chicago and St. Louis are losing the most workers overall and are attracting most new workers from their regions rather than internationally.

"That presents a problem for cities like Chicago; cities need the best and brightest to strengthen their economies, and top performers want to work with other top performers and top companies," the LinkedIn report said.

The report comes two days before the Labor Department releases its closely watched monthly employment data.