Combining information from labor historians and using techniques from finance we analyze the strikes that labor historians have agreed are pivotal in American history' during the period 1925-1937. Using information we collected on strike dates and historical financial market stock price data we assess the financial market's view of these conflicts. We study the effects of major strikes between the world wars on detailed industry stock prices. We find that strikes have large, negative effects on industry stock value. We also find that longer strikes, violent strikes, strikes where unions win,' industry-wide strikes, strikes that lead to union recognition, and strikes that lead to large wage increases lead to larger negative share price reactions than other strikes. Also, our analysis shows that most of the news' in a strike seems to be incorporated very early on in the strike. Our analysis strongly suggests that although the financial markets generally expected unions to lose,' they viewed union victories as quite important determinants of the share of firm profits going to stockholders.