A new report gives a sobering view of the challenges that children of North Carolina’s low-income families face in improving their economic status in early adulthood. Children of families reporting household income of less than $30,000 a year in 77 of the state’s 100 counties will probably have lower annual earnings by age 26 than the national average, according to a study released in April by The Equality of Opportunity Project, a collaboration by Harvard University economics professors Raj Chetty and Nathaniel Hendren. That’s higher than the national rate: Children from 62% of counties earn less than the average in early adulthood. The map above shows the percentage gain or loss in income for children of low-income families growing up in North Carolina. The project studied the outcomes of children who were born between 1980 and 1986. Davie County rated highest in North Carolina for upward mobility of low-income children — the only county in the state that ranked in the top half of counties nationwide. Forsyth County was third worst in the nation, and Mecklenburg ranked 99th among the largest 100 U.S. counties, surpassing only Baltimore County, Md. In general, North Carolina’s larger metro areas did not show improvement in the fortunes of low-income children. Those growing up in Mecklenburg, Wake, Guilford, Forsyth, Cumberland, Durham, Gaston, New Hanover and Buncombe counties would earn at least 11% less than the U.S. average at age 26.