Because the event that May 1st commemorates is a Chicago police riot involving massacre of labor activists, and the subsequent framing and execution of several anarchists during the struggle for the eight-hour day. The American government would rather forget. http://en.m.wikipedia.org/wiki/Haymarket_martyrs We still have commemorative protests but they either end up small and inconsequential (cause everyone's at work) or they fall subject to police repression. Americans' union membership is about 1 in 8 as mentioned in the article. This is a significant decline from the historical peak of 1 in 3.A little off-topic, but why is it that Labor Day in the US is not celebrated on May 1st as in much of the rest of the world?
Also, as a non-US resident, how common is it to be a member of a union? Are you in a union?
The intensity of May day protest in the U.S. are pretty dependent on where you are. Most the country you will see no significant pro-labor action at all. A few extremely liberal cities can still boast that they have any meaningful labor day observance. Portland Or. does ok, Cambridge Ma. had a significant labor day parade that focused on worker rights and a general grab bag of liberal issues. I'd guess that the only place in Texas that might have a labor day turn out would be Austin? In response to Wonton, the U.S. media mostly villainizes any pro-labor sentiment and your average candidate would be crucified at election time if they had anything nice to say about organized labor. Labor day is a holiday for the bourgeoisie and the owners of capital. The only real laborers that get the day off work for various state, local or federal government agencies with the exception of people that work for banks and a tiny sliver of union workers.