As with most legal questions, the correct answer is "it depends."

For certain purposes, the federal government is a person: U.S. v. The Cooper Corp., (1941).

In some contexts, city/county governments are, but state or federal governments are not because they are sovereigns. Cook County v. U.S. ex rel Chandler, (2003). This actually makes sense because most municipalities are "incorporated" in the sense that they're creatures of state law.