For more than a century, labor unions have been a critical constituency for the Democratic Party, while Republicans have tried to curb unions’ influence. Wherever you fall on the political spectrum, if you have Monday off, you can thank those unions.

Labor Day began in New York City — a “workingmen’s holiday,” first celebrated by the Central Labor Union in 1882; in 1894, it became a national holiday.

Since then, unions’ influence has ebbed. But in New York, labor unions maintain more power, and more membership, than they do in any other state. More than a quarter of all workers in New York are represented by unions, according to the Bureau of Labor Statistics, the highest rate in America. Alaska and Hawaii are the only other states where more than 20 percent of the workforce is represented by unions.

States with higher union membership also have higher average weekly wages: The BLS says the average weekly wage in New York in the fourth quarter of 2013 was $1,266 — 26 percent higher than the U.S. average.

And New York unions are still flexing their political muscles. The state legislature passed a minimum-wage increase in 2013, gradually raising the rate to $9 an hour by the end of 2015. Unions also put a big effort into electing progressive New York Mayor Bill de Blasio, and the city’s teachers union and city workers unions scored promising new contracts this year.

The New York legislature was the first to consider making Labor Day an official holiday, though Oregon’s lawmakers passed a bill first. U.S. Sen. Robert Wagner (D-N.Y.) was the lead sponsor of the 1935 National Labor Relations Act, which permitted private-sector workers to unionize and bargain collectively. His son, Robert Wagner Jr., allowed public-sector collective bargaining when he was mayor of New York City.

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