Having two total eclipses cross the continental United States only seven years apart is a rarity. Before 2017, the last total eclipse to cover this much American territory was in 1970, when the moon's shadow moved out of the Gulf of Mexico, across the Florida Panhandle, and up the East Coast. And it will not happen again until 2045, when the shadow comes ashore on the northern California coast and races southeast across the Great Plains and over the Florida peninsula.