Cinnamon was just one staple stored in the commissary at Fort Larned for the troops stationed there in the mid-1800s.

Everyone could use a little cinnamon for their toast or buns, but a keg of the spice? Which unit of the National Park System would require so much?

Almost 15 million Canadians and more than 3.5 million Americans live within a three-hour drive of Thousand Islands National Park and more than 35,000 vehicles pass by it daily on Hwy. 401, but the Ontario park only sees about 80,000 visitors a year.

A road trip of roughly 2,500 miles led me to four intriguing units of the National Park System that, while not at the top of everyone's go-to list, revealed both rich and troubling chapters of American history that likely would have faded into irrelevance without the parks that interpret their stories.