Britain grew up in the Finger Lakes region of New York State, where she started her first novel - an undersea fantasy featuring herself and her friends - at the age of nine. She published her first book, a cartoon collection called Horses and Horsepeople, at the age of thirteen.
After completing her degree in film production, with a minor in writing, at Ithaca College in 1987, she went to work for the National Park Service in 1988 after a conversation with a park ranger during a visit to Women's Rights National Historical Park. She got her first seasonal ranger job at Clara Barton National Historic Site site in Maryland.At the time of the publication of her first novel, Green Rider, she was working full-time as a park ranger at Acadia National Park, and she drew much of the inspiration for the landscape of Sacoridia from the park. Her many years as a park ranger enabled her to work in a variety of natural and historical settings, from 300 feet below the surface of the Earth to 13,000 feet above sea level on the Continental Divide; and from the textile mills of the American Industrial Revolution to the homes of Americans who changed the course of history.
Currently she lives in a log cabin on Mount Desert Island off the coast of Maine where she writes full time and pursues interests in reading, guitar playing, canoeing, and cartoon illustration, supervised by two cats and a dog.