Workers assemble Nissan pickup trucks on the production line at the Nissan manufacturing plant in Smyrna, Tenn.

Higher-paying manufacturing jobs lost during the 2008 recession have been replaced by lower-wage jobs, according to a report released Monday by the United States Conference of Mayors.

(Josh Anderson, New York Times file photo)

While 8.7 million jobs have been regained since the 2008 recession, they are paying much less, by an average of 23 percent, according to a report released Monday by the United States Conference of Mayors.

The report comes as debate continues about income inequality in the United States.

"While the economy is picking up steam, income inequality and wage gaps are an alarming trend that must be addressed," said Conference of Mayors President Kevin Johnson, the mayor of Sacramento, Calif., in a news release. "We cannot put our heads in the sand on these issues."

The annual wage in sectors where jobs were lost, particularly in manufacturing and construction, during the recession was $61,637, but the average wage of new jobs through the second quarter of 2014 is $47,131, the report shows.

It represents a loss of $93 billion in wages, according to the report. (Go below to see the full report. Mobile users can see it here.)

The losses in construction and manufacturing were replaced by jobs in hospitality, health-care and administrative support.

The report shows the gap between low- and higher-income households is growing and likely will continue in the future. In 2012, the latest year for which figures are available, 73 percent of metro areas had a larger share of poorer households (those making less than $35,000 per year) than upper-income households of above $75,000.