As a country, it can be said that the United States are composed of two types of government in terms of their scope of influence: state and federal governments. State-level governance manages the citizens who are living in that state, especially in terms of the applicable laws, while federal-level governance manages citizens country-wide. Historically, federal governments have more influence than state governments.
The answer to the question is that these factors have influenced the federal government’s influence over time: (1) changes in how the U.S. Supreme Court and others have interpreted the U.S. Constitution, (2) changes in the power of the purse, (3) changes in what the people (i.e., citizens, interest groups, and political parties) want the federal government to do, (4) changes in the number, size, and resources of federal bureaucratic agencies, and (5) amendments to the U.S. Constitution.