To begin with, think about what your keywords really mean, and don't sort them at first. Start by writing down any word you think of associated with the topic.
If you need help with this, there are a couple of places you can go:
After you have as many keywords as you can think of, sort them into categories, or arrange loose associations using a spider map, or other brainstorming tool (try a mindmapping app to begin).
For context newspaper articles, see ProQuest Historical Newspapers
For more information on keyword development and brainstorming, see the Undergraduate Research and Writing tab/page.