This paper examines differences in costs among union and nonunion firm
s operating in the multiple and competitive lumber markets; develops a
model of output and product selection decisions; and then estimates t
he cost function implied by the model for a sample of sawmills that pr
oduce green and dry lumber. Overall, the average variable costs for th
e green technology are about 67 percent higher for union mills and, fo
r the dry technology, costs are about 30 percent higher. However, diff
erences in minimum average variable costs are negligible in the dry ma
rket but are significant in the green market. The results suggest that
some union mills may be able to coexist with nonunion mills in a comp
etitive industry by specializing in market niches determined by compar
ative cost advantages.