Step onto the sewing floor at the Texsun SA plant in Guatemala City, and it’s as if you waded into a fast-moving river of apparel production.
 
Scores of employees—mostly women, but a number of men as well—sit or stand at sewing machines, cutting equipment, ironing stations and other tools of the garment trade. Fingers fly and elbows swing rhythmically amid a low-pitched chorus of whirs and pops, plus the rhythmic staccato of sewing machines punching thread through fabric to make casual knit shirts—mainly for the U.S. market.
 
The eight production lines on this rectangular-shaped ...