WASHINGTON May 1 is a day to celebrate the start of spring and the freedom for working people to do what they want on nights and weekends.

May Day has long been known as International Workers Day because of something that happened as workers fought for shorter hours, which used to be one the foremost demands of the American labor movement.

Hundreds of thousands of workers went on strike on May 1, 1886, in an effort to win eight-hour workdays. Police cracked down on the strikers, and someone threw a bomb at officers during a protest several days later in Chicagos Haymarket Square. Authorities fired on the crowd and arrested hundreds of people. The government wound up blaming anarchists for the violence and executed four of them.

People typically worked more than 60 hours per week back then, including on Saturdays. Workers had gone on hundreds of strikes over the decades in an effort to get those hours down, arguing that they needed time off for recreation and that shorter workdays would spread work around and therefore reduce unemployment.

So long as there is one who seeks employment and cannot find it, the hours of labor are too long, American Federation of Labor President Samuel Gompers said sometime in the 1880s.

Labor leaders moved away from general strikes after the Haymarket Affair but continued pushing for shorter hours. Their efforts culminated in the federal Fair Labor Standards Act of 1938, which essentially enshrined the 40-hour week by requiring employers to pay overtime to employees on the job more than 40 hours in a week.

Workers continued pushing for shorter hours, but the movement fizzled after the 1930s and has basically been replaced by demands for a higher minimum wage. Republicans have recently proposed allowing employers to compensate overtime with taking off time later, or comp time an idea labor experts say businesses would simply use to avoid having to pay overtime.

The average workweek for a full-time U.S. worker is 42.5 hours, according to the Labor Department . If it hadnt been for the shorter hours movement, the average workweek would probably be a lot longer. And if the shorter hours movement hadnt evaporated, the workweek would probably be shorter today.

In recent years, activists have used May Day to rally for immigrants rights. Labor organizers said they hoped Monday would see the largest participation in strikes around the country since similar protests happened in 2006.

May Day is a beautifully American holiday, one created by American workers, crushed by the American government, incubated abroad, and returned to the United States by immigrant workers, historian Jacob Remes wrote for AlterNet in 2012 .

Arthur Delaney is a co-host of So That Happened, the HuffPost Politics podcast.