Shutting down a highway, and presumably interstate commerce, would technically move them into Federal Jurisdiction, no?
> specific federal law that would apply to people blocking a highway
18 U.S. Code § 1951. Interference with commerce by threats or violence
(a) Whoever in any way or degree obstructs, delays, or affects commerce or the movement of any article or commodity in commerce, by robbery or extortion or attempts or conspires so to do, or commits or threatens physical violence to any person or property in furtherance of a plan or purpose to do anything in violation of this section shall be fined under this title or imprisoned not more than twenty years, or both.
https://www.law.cornell.edu/uscode/text/18/1951