Nowadays, many think of the Labor Day holiday in the U.S., which falls on the first Monday in September — Sept. 2 in 2019 — as a day for cookouts or shopping deals. But its origins date back to two gatherings of another, more politically motivated sort.

One was a “monster labor festival” featuring of a parade of unions and accompanying picnic, which took place on Sept. 5, 1882, in a New York City park. That gathering is thought to have attracted as many as 10,000 marchers, according to Linda Stinson, a former Department of Labor historian. They listened to speeches in support of workers’ rights, and — in lighthearted activities more in the spirit of what goes on today — people drank beer, danced and set off fireworks.

The other event was a darker one. On May 11, 1894, in a company town outside Chicago, employees of the railway sleeping car mastermind George Pullman went on strike when their wages didn’t go up after the economy tanked. In a show of solidarity, the American Railway Union — said to have boasted 150,000 members at the time and led by famous socialist Eugene Debs — refused to operate Pullman train cars, snarling mail delivery and prompting President Grover Cleveland to send in federal troops to break up the strike. Rioting and arson broke out, and it evolved into what’s now considered one of the bloodiest episodes in American labor history.

A national Labor Day holiday was declared within months.

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Some experts say Cleveland supported the idea of such a holiday, which already existed in several states, in an effort to make peace with the unions before he ran for re-election. (He would lose anyway.) But perhaps one of the most eloquent explanations of why the federal government saw fit to declare the holiday can be found in a Congressional committee report on the matter.

Sen. James Henderson Kyle of South Dakota introduced a bill, S. 730, to Congress shortly after the Pullman strike, proposing Labor Day be the first Monday in September. Here’s how Rep. Lawrence McGann (D-IL), who sat on the Committee on Labor, argued for the holiday in a report submitted on May 15, 1894:

The use of national holidays is to emphasize some great event or principle in the minds of the people by giving them a day of rest and recreation, a day of enjoyment, in commemoration of it. By making one day in each year a public holiday for the benefit of workingmen the equality and dignity of labor is emphasized. Nothing is more important to the public weal than that the nobility of labor be maintained. So long as the laboring man can feel that he holds an honorable as well as useful place in the body politic, so long will he be a loyal and faithful citizen. The celebration of Labor Day as a national holiday will in time naturally lead to an honorable emulation among the different crafts beneficial to them and to the whole public. It will tend to increase the feeling of common brotherhood among men of all crafts and callings, and at the same time kindle an honorable desire in each craft to surpass the rest. There can be no substantial objection to making one day in the year a national holiday for the benefit of labor. The labor organizations of the whole country, representing the great body of our artisan population, request it. They are the ones most interested. They desire it and should have it. If the farmers, manufacturers, and professional men are indifferent to the measure, or even oppose it, which there is no reason to believe, that still would constitute no good objection, for their work can be continued on holidays as well as on other days if they so desire it. Workingmen should have one day in the year peculiarly their own. Nor will their employers lose anything by it. Workingmen are benefited by a reasonable amount of rest and recreation. Whatever makes a workingman more of a man makes him more useful as a craftsman.

Cleveland signed the bill into law on June 28, 1894.

Now, more than a century later, Labor Day is firmly entrenched on the American calendar — but it does still come with at least one, much smaller, controversy: the old fashion debate over whether it’s taboo to wear white after Labor Day.

Write to Olivia B. Waxman at olivia.waxman@time.com.