Difference between median weekly earnings of union members and non-members, full time workers, 1999 Earnings of Earnings of Difference Percent union members non-union in dollars difference workers Total 672 516 156 30.2 Private 633 510 123 24.1 Nonagricultural 634 513 121 23.6 Construction 778 509 269 52.8 Government 714 585 129 22.1 Transportation and public utilities 748 613 135 22.0 Trade 499 418 81 19.4 Manufacturing 614 561 53 9.4 Services 554 515 39 7.6 Finance, insurance, and real estate 582 599 -17 -2.8 Mining 710 735 -25 -3.4