The hypothesized relationship between economic expansion and accident injuries is tested using archival economic and accident data from the Los Angeles-Long Beach, California metropolitan area. The association is measured using cross-correlation techniques after variation shared with a comparison metropolitan area (Anaheim-Santa Ana-Garden Grove) is removed. Two tests of association are conducted. The first uses the raw accident rate of the comparison metropolitan area as a control variable while the second adjusts the control variable to reflect shared industrial sectors. Findings suggest that the incidence of disabling accidents increases in the month before and during the month that the manufacturing work force expands. The impact appears strongest during the month that new workers are added.