Greetings!
Probably your best source of information is going to be your school's library. You should have a user name and password to access the library's databases. Once you're in, you can find sources by using your search terms, as you would with any internet search: "terrorism voting trends" "terrorism impact elections" ... play with different combinations of search terms to find what you need. Look in databases which contain scholarly journals with articles and research results on the topic. If you are able to go to the library in person, ask a librarian for assistance; they can be remarkably helpful.
Before getting too deep into your research, you might want to be thinking about what your thesis statement will be; this can help direct your research. On the other hand, sometimes what you find will cause you to change the focus of your thesis a little. You have a fairly specific focus for your paper, but generally a paper of this kind will have a thesis statement which takes a position on the subject. For example, you might want your thesis to be something like "Traumatic events such as terrorist attacks have a significant impact on voting trends in a community, influencing election results significantly." If your research showed otherwise, you could change your thesis to reflect that.
I hope this helps get you started! If you'd like to post your rough draft once it's written, I'd be happy to have a look and give you suggestions!
Thanks,
Sarah, EssayForum.com
Sarah, EssayForum.com