Maggie is a victim of her environment. Born to poverty and to a mother who, because of the dejection of that poverty, as turned to alcohol, Maggie begins life with two strikes against her. Because she is a woman and because she does not have money for education, Maggie has very few prospects for improving her condition.
The only way a girl at the time could improve her condition would be through a suitable marriage - but how is it possible to find a suitable marriage when you live among “a worm of yellow convicts . . . [who crawl] slowly along the river’s bank.” Pete seems like a good prospect to Maggie, but his arrogance insists to him that he deserves what he asks for. Maggie clings to him with hope for the future, and because she is afraid of losing him, gives herself to him.
The result is Maggie's shame - not Pete's, of course, just Maggie's. She is turned out by her family and ignored by her neighbors. She has even fewer prospects for jobs because her reputation has been tarnished. She has no escape, and turns to prostitution just to say alive.
This is a scathing criticism by Crane of life in the city. He insists to readers through Maggie that the cruel urban standards squashes free will and innocence, thrives on hypocrisy, and brutalizes its inhabitants.