On March 12, a rank-and-file caucus of Branch 36 (Manhattan-Bronx) of the National Association of Letter Carriers (NALC) spearheaded the demand for a branch strike vote. Striking the federal government has been illegal since 1912. But that is exactly what Branch 36 voted to do on March 17. Picket lines went up at midnight all over New York City. Other NALC branches voted to strike, spreading upstate and into New Jersey, Massachusetts, Connecticut, Pennsylvania; then west to Ohio, Illinois, Michigan, Colorado, and California. Together they shut down 671 post offices in dozens of cities and...