North embarked on his literary journey with a spirited focus on fiction aimed at young readers. Yet, as the 1950s and 1960s unfolded, he pivoted towards biography, a genre that allowed him to delve into the lives of notable Americans celebrated for both their achievements and indomitable personalities. His biographical works during this period showcased a variety of figures, such as Abraham Lincoln in Abe Lincoln: Log Cabin to White House (1956), George Washington in George Washington, Frontier Colonel (1957), and Thomas Edison in Young Thomas Edison (1958). He also brought to life the adventures of historical figures in books like Captured by the Mohawks, and Other Adventures of Radison (1960) and explored the world of Mark Twain in Mark Twain and the River (1961). These works were crafted with the young adult demographic in mind, aiming to inspire and educate through the lens of historical narratives.

In 1963, North took a more personal turn with the publication of Rascal: A Memoir of a Better Era, an autobiographical account that interwove his affection for raccoons with reflections on his past. This memoir marked a shift in his literary focus, as subsequent works revolved around stories featuring these animals.

Among North's most enduring contributions is Thoreau of Walden Pond, a juvenile biography that has become a cornerstone in the genre. It adeptly translates the life and philosophies of Henry David Thoreau into terms accessible to young readers. By presenting Thoreau not merely as a historical figure but as a thinker with relevant ideas, North offers a window into the Transcendentalist philosophy. Notably, in chapters like “A Walden Character,” North opts against mere paraphrasing or fabricated dialogue. Instead, he chooses authenticity by incorporating direct excerpts from Thoreau's Walden. This approach lends a genuine voice to Thoreau’s thoughts, allowing young readers to engage directly with the philosopher's ideas in a way that is both enlightening and comprehensible. As such, Thoreau of Walden Pond serves as an excellent introduction for those venturing into the study of Thoreau and his ideologies.