Yeah 4 levels of folders, and each one has a style1.css file in it. Would renaming the css files for each specific directory help?
Are they duplicate style sheets or are there differences? As Lucy pointed out, your file structure could be a problem, especially if there are some variations between the style sheets. A page may have the linked style sheet at style1.css when it maybe should be ../style1.css.
One solution is to make one main style sheet and do either <link rel="stylesheet" type="text/css" href="/main.css" /> or <link rel="stylesheet" type="text/css" href="http://www.YOURDOMAIN.com/main.css" />
Another option is have one style sheet for all the "general" styling and specific ones for everything else, e.g. listing.css category.css city.css state.css
And assign them to their relevant pages, but again watching their link path.
Unless you have different style sheets for different media, having multiple sheets, especially with the same name, can be difficult to manage.