Once you have selected a topic and discussed it with your instructor you will want to start your research. To start looking for materials in American History you should start with two items:
These two items serve different purposes.
Is a listing of the most important books in the English language by topic, and thus is invaluable to learning what is the past scholarship in the field, including what are some of the debates and who are the leading scholars on a specific topic. Using relevant titles gleaned from these volumes you can then check them against NYU Libraries Catalog to find out not only if the library owns the book, but also what the Library of Congress considers the subject(s) to be.
Using these library subject headings in the catalogue will give you a number of other published works, but also -- and importantly -- similar books published since the Guide to Historical Literature.
The sections devoted to the United States are all in volume 2.; Here is a breakdown of the entries by section title and number. There is a section "Native Peoples of the Americas" and I include the numbered entries specifically on the United States. The section on Colonial North America does include British, Dutch and French colonies but excludes the Spanish colonies (in Section 37, Latin America to 1800).
You should also mine the bibliographies of the books you find in Bobst to identify more works, but also relevant primary sources such as newspapers, archival and manuscript collections and published works such as diaries, memoirs, etc.
Is the source for periodical literature in American and Canadian Studies (not just history) and includes not just English language scholarship but also works in over fifty languages -- from Afrikaans to Yiddish. Because it is on-line you can also search it using keywords, or use AHL's own subject headings to explore and find more works. AHL has a growing body of full-text but also contains references to material that is available to you in other formats, including H-Net reviews.You can identify reviews of the books you have picked to find out where other scholars have agreed or disagreed with their findings.
Aside from these two items, what other bibliographies and databases you chose to use will largely be driven by your specific research. This research guide tries to help guide your selections amongst in the vast number of available sources.
There are two principal professional societies of historians in the United States: the American Historical Association (AHA, founded in 1884) and the Organization of American Historians (OAH, founded in 1907). Both publish scholarly journals, provide relevant news for their members, and hold conferences. As its name implies, the OAH focuses on the history of the United States but it also looks at the United States in a global context. The AHA covers the world, including the United States.
Every state also has a historical organization which focuses on the history of that state. In addition, there are organizations that focus on regions of the United States, other regions and nations of the world, specific periods of time, and/or historical fields, such as African-American, diplomatic, labor, military, religious, urban, and women's history. The variety is infinite.