The Oregon Trail was a 2,170 mile (3,490 kilometer) route that connected the Missouri River to valleys in Oregon. It was laid by fur trappers from about 1811 to 1840. It was originally only passable by horse or by foot, but the first wagon train was organized in 1836 and a wagon trail was cleared from Missouri to Idaho. Wagon trails were then cleared increasingly westward until they reached Oregon, and by that point the Oregon Trail was complete. Use of the trail declined as the first transcontinental railroad was completed in 1869. By the 20th century, the Oregon Trail was replaced by paved highways, including some that followed parts of the same route.
In 1850, Daniel Clayton traveled from New Jersey to Wyoming, on a butterfly expedition, by way of the Oregon Trail. He met a frontierswoman named Martha O'Brien and named a new species of butterfly Lepidoptera martha, after her. They were married on March 3, 1850 in Wyoming. Afterward, Martha went back with her new husband to New Jersey, where she gave birth to a daughter, Clara, five years later.
In 1991, Clara's sons Jules and Verne, along with Marty McFly, travel in the DeLorean time machine to Wyoming on Daniel and Martha's wedding day. Upon meeting Martha, she falls in love with Marty, at which point Jules and Verne realize that they have to get their grandparents back together or they will never be born. When Clara begins to fade from existence, and Doc Brown notices that the wagon buckboard that normally is inscribed with the Clayton's wedding day is blank, he heads back to that date in the Jules Verne Train. After Martha and Jules are kidnapped by "Wild Bill" Tannen, they escape, but are pursued by a grizzly bear. Doc instructs them to throw a buffalo hide over the Old Faithful geyser, and the water elevates them up and out of danger. At that point, Daniel overcomes his timid nature to team up with Doc to save them, flying them out of danger with a homemade glider. Upon realizing that he risked his life to save her, Martha falls in love with Daniel, and the timeline is restored.
- Back to the Future: The Animated Series
- Episode 13: "Clara's Folks" (First appearance)
- Back to the Future: Untold Tales and Alternate Timelines
- Issue 5: "Clara's Story" (Mentioned only)