By PATRICIA COHENMAY 29, 2017 STORM LAKE, Iowa — When Dan Smith first went to work at the pork processing plant in Storm Lake in 1980, pretty much the only way to nab that kind of union job was to have a father, an uncle or a brother already there. First was Hygrade Food Products Corporation, an old-style meatpacking house that introduced Ball Park Franks to the Detroit Tigers’ stadium in 1957 and operated the Storm Lake plant when Mr. Smith went to work there. Decades ago, the picturesque city of Spencer, about 40 miles north, spurned the overtures of a packing plant, with some residents saying at the time that they didn’t want their town to turn into Storm Lake. Mr. Smith, looking back on his decades at the plant, acknowledges that a supply of immigrants makes it easier for employers to pay less, but he doesn’t begrudge them the work. “It was the best-paying job you could get, 100 percent, if you were unskilled,” said Mr. Smith, now 66, who followed his father through the plant gates.