IANAL but I would assume that public roads are public property throughout the USA, but of course there can be private roads on private land, often posted as no trespassing, in addition to gated communities. Sometimes public access or access by another property owner is part of a property right when land is sold. Sometimes a public street can be blocked, for example if there's a permit for a block party or sometimes for private construction work, so I don't know whether some jurisdiction (as opposed to an individual without a permit for a specific purpose) could block access. OTOH, a property owner can be obligated to remove snow and maintain public sidewalks in good condition in front of one's own property as well as maintaining the strip of grass some places have between the sidewalk and the street. I don't know who owns the land under the sidewalk and suspect the answer depends on the state or locality.

Another interesting example is whether beaches are public or private property and whether access must be allowed. For example, I know of small towns on the (USA) coast that don't like the idea of public beach access, so they just post the entire place with no parking signs for no apparent reason and property owners don't permit outsiders to walk or bike through their land to get to the beach.