In E. L. Doctorow's Book of Daniel I read the following sentence:
The state police brought Susan in off the turnpike and that makes her a public charge.
Susan is an inmate of a mental institution in 1967 and the person, who says this (her brother) seems to be a hippie.
What does off the turnpike mean (what did Susan do before the state police brought her into the asylum) ?
Update 1 (22.05.2015 15:46 MSK):
Later in the book I read
Why do two state cops, finding a young girl bleeding to death in the ladies' room of a Howard Johnson's take her not to the nearest hospital, but to the nearest public insane asylum?
Howard Johnson's is probably a motel, which is located near a toll road (turnpike).