Union Square marks the ‘union’ of two old roads, not a labour union.
The square lies where Bloomingdale Road (now Broadway) met the former Bowery Road: ‘here was the union of the two principal thoroughfares of the island’. First a public commons called Union Place, it was renamed Union Square in the early 1830s at the urging of developer Samuel Ruggles. 14th Street, its southern edge, was the southernmost of the 15 wide crosstown streets of the 1811 grid plan.