"Although the United Mine Workers of America (UMWA) has always advocated strongly for miners' safety, the empirical literature contains no evidence that unionization reduced mine injuries or fatalities during the 1970s and ‘80s. The author uses an updated methodology and a more comprehensive data set than previous studies to examine the relationship between unionization and underground, bituminous coal mine safety from 1993 to 2010. She finds that unionization predicts a substantial and statistically significant decline in traumatic injuries and fatalities, the two safety measures that are the least prone to reporting bias. These results are especially pronounced among larger mines. Overall, unionization is associated with a 14 to 32% drop in traumatic injuries and a 29 to 83% drop in fatalities. Yet unionization also predicts higher total and nontraumatic injuries, suggesting that injury reporting practices differ between union and nonunion mines."

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