Book Reports / a question concerning the american literature thesis [2]

hello everyone,

this is my first post here, and i hope that someone can help me, i'm a second year master student and i have to present a dissertation of about 50-60 pages about any theme in american literature, but i just can't find any good thesis statement to discuss, in addition to that i don't know how to develop the idea and divide it into chapters...i just want some ideas to have an idea about the kind of themes and ideas discussed in this field of study ...

thank you