"Explores the California Gold Rush by examining the causes leading up to it and the immediate and lasting effects it had on the people and places involved"--
"Examines the Oregon Trail by discussing how and why it came to be and the immediate and lasting effects it had on the nation and the people who traveled it"--
"Examines the Wilderness Trail (i.e., the Cumberland Gap) by discussing how and why it came to be and the immediate and lasting effects it had on the nation and the people who traveled it"--
"Examines the expedition of the Donner Party by discussing how they came to be stranded in the Sierra Nevada Mountains and the immediate and lasting effects their journey had on the nation as well as the people and places involved"--