Green’s Dictionary of Slang

(US) any centre of urban life, typically Union Square, New York City, or Washington Square, Chicago, where tramps, vagrants, the more or less deranged and any other eccentrics gather.

1918		DN V 440: bughouse square, n. Washington Square, Chicago, where soap-box socialists disseminate their economic gospel for the salvation of the downtrodden.
1923		N. Anderson Hobo 9: Washington Square is the center of the northern area. To the ‘bos’ it is ‘Bughouse Square’.
1931		Irwin Amer. Tramp and Und. Sl. 39: bughouse square. Washington Square, Chicago; so called since there assemble those of the fraternity of the road, and others, who think they have a message for the world. The name has lately been applied to Union Square, New York, and for the same reason.
1948		R. Chaplin Wobbly 71: We made the acquaintance of the rough-and-ready free-lance orators at ‘Bughouse Square’ [DA].
1956		F.O. Beck Hobohemia 67: This matchless Bug House Square in the heart of Chicago, a pocket edition of Greenwich Village, is a city block, really square, on the near north side where the Gold Coast meets the slums.
1958		W. Motley Let No Man Write My Epitaph (1960) 197: They hung around listening to the speakers in Bughouse Square.
1962		Ragen & Finston World’s Toughest Prison 792: bug house square – Washington Square, Chicago.
1991		(con. 1920s) O.D. Brooks Legs 86: Washington Park was the centre of this stem. The bums called it Bughouse Square, because on warm days and evenings many of the habitués mounted soapboxes and harangued their audiences on everything from religion to revolution.
2005		E. White My Lives 117: ‘Bughouse’ Square, an open park [in Chicago] covered with old trees where stump speakers harangued small crowds about crank causes.