As we head into the long Labor Day weekend, it's a good time to take a look at why this coming Monday is a holiday in the first place. Labor Day was declared a national holiday in 1894, but it was first celebrated in 1882 in New York City, with a huge picnic and procession. In the years that followed, the labor movement gained strength in the city, particularly in the wake of such events as the Uprising of the 20,000—one of the largest workers' strikes in the country's history—and the Triangle Shirtwaist Factory fire, a tragic event that brought to light the abhorrent conditions that many workers toiled under. Workers gathered for meetings in Greenwich Village, and staged protests at parks throughout the city—and many of those places can be found in modern-day New York City. For a better understanding of the city's role in the labor movement, check out the map below—and let us know what we left out, either in the comments or through the tipline.