The power the Teamsters built was based in constant organizing and growth in trucking and in the sites of pickup and delivery for the drivers. This depended on the opportunity gained from the threat of secondary pickets--when drivers came across pickets at a gate and refuse to deliver or pick up at a factory, warehouse, or store, created pressure on the employer to allow the goods to move--at any cost. The cost, of course, was a Teamster contract [...] But trucking was not the only sector of the economy impacted by the innovations of the Teamsters. The actions of these drivers at strategic sites moved Teamster organizing into manufacturing, food processing and dairies, coalmines and sawmills. Pickets at delivery sites made warehouse workers and retail workers into union members.