How does Alice Walker break the rules" of literature with The Color Purple?"

Sometimes, authors purposefully abandon traditional writing techniques. As readers, we expect to know when a story starts, how much time lapses until the end, and if there are any gaps in between. But sometimes, a good author can break these rules and make it work. The Color Purple, by Alice Walker, is one such book.
Walker's style certainly doesn't make this book an easy read. Instead of chapters, the novel consists of a series of letters (making it an epistolary novel), none of which are dated. In order to have a time frame for the novel, you need to read it carefully and watch for clues. For example, the book begins in a period when people ride around in wagons, but ends with people driving cars. Thus, the time span of the novel is about 40 years. Additionally, you need to realize that spans of five years fall between some of the letters, but the author does not reveal this information. You must compare the letters to gather this information.