This is not collage, because the assorted elements are not reduced to static snapshots of the city. Instead, they appear and pass away as O'Hara walks through them. The effect is something like a motion picture, with O'Hara in each frame. Saying what all the details mean is easy--they mean whatever they are, and their importance lies in their randomness and transience. . . .
Everything has equal significance--Puerto Ricans, dead friends, a warehouse--and O'Hara, caught up in the fullness of such a fife, returns to work with a book of poems in his pocket, his ruminations having led neither to sadness nor happiness but to an affirmation of his place in the teeming city-world.
From "The City Limits" in Jim Elledge, ed. Frank O’Hara: To Be True to a City. University of Michigan Press, 1990.