May 1, 2012 (29 images)

Veronica Romo (C) joins about 1,000 protestors who marched through the streets on May 1, 2012 in Chicago. Marchers voiced their support for workers' rights and immigration reform and spoke out against corporate greed and Wall Street as part of International Workers Day, a commemoration of the 1886 Haymarket Riot in Chicago. UPI/Brian Kersey

Police and demonstrators clash during a May Day protest in Oakland, California on May 1, 2012. Police made arrests and threw tear gas. UPI/Terry Schmitt

Arizona Diamondbacks second baseman Aaron Hill jumps over Washington Nationals Steve Lombardozzi as he turns a double play during the sixth inning at Nationals Park in Washington, D.C. on May 1, 2012. UPI/Kevin Dietsch

Philadelphia 76ers forward Thaddeus Young (L) fouls Chicago Bulls center Joakim Noah as he drives to the basket during the fourth quarter of game 2 of the first round of the Eastern Conference Playoffs at the United Center on May 1, 2012 in Chicago. The 76ers won 109-92 tying the best of seven series 1-1. UPI/Brian Kersey