Q. Historical data on wages in an industry in the U.S.?

Establishment Payroll Data by broad industry sector is collected by the Bureau of Labor Statistics (BLS).

Labor Productivity and Cost Data by NAICS or SIC code from 1992 on are made available by BLS.

Sage Data also provides personal income and earnings by SIC and NAICS at the national, state, and county levels.

The BLS Quarterly Census of Employment and Wages gives average annual pay, average weekly pay and total wages by NAICS code, by geographic area and establishment size.

Also try Prices and Wages by Decade (courtesy of University of Missouri).  Covers 1700+.