link discusses the idea of the right to travel and includes some case references which have been used to support the claim that U.S. Citizens have a general "Right to Travel".
EDIT: Some specific judicial opinions:
"The right of the citizen to travel upon the public highways and to transport his property thereon, either by carriage or by automobile, is not a mere privilege which a city may prohibit at will, but a common right which he has under the right to life, liberty, and the pursuit of happiness." Thompson v. Smith, 154 SE 179.
"Undoubtedly the right of locomotion, the right to move from one place to another according to inclination, is an attribute of personal liberty, and the right, ordinarily, of free transit from or through the territory of any State is a right secured by the 14th amendment and by other provisions of the Constitution." Schactman v. Dulles, 96 App DC 287, 293.