The Highways in Hiding, also known as the Todash Highway, are a series of roads that allow one to travel between the Multiple Americas by taking the traveler "todash". Each version of the world is only slightly different from the previous. The highways are usually hidden to passerby.
Father Callahan traveled far along these highways after he fled from Jerusalem's Lot. He found versions of Earth where Spiro Agnew and a man named Chadbourne became president and ended up on the ten dollar bill. Callahan said that the highways became addicting after a time. It was hard for him to give up his wanderings.