A distinct set of definitions for the word republic evolved in the United States. In common parlance a republic is a state that does not practice direct democracy but rather has a government indirectly controlled by the people. This is known as representative democracy. This understanding of the term was originally developed by James Madison, and notably employed in Federalist Paper No. 10. This meaning was widely adopted early in the history of the United States, including in Noah Webster's dictionary of 1828. It was a novel meaning to the term, representative democracy was not an idea mentioned by Machiavelli and did not exist in the classical republics.[48]

The term republic does not appear in the Declaration of Independence, but does appear in Article IV of the Constitution which "guarantee[s] to every State in this Union a Republican form of Government." What exactly the writers of the constitution felt this should mean is uncertain. The Supreme Court, in Luther v. Borden (1849), declared that the definition of republic was a "political question" in which it would not intervene. In two later cases, it did establish a basic definition. In United States v. Cruikshank (1875), the court ruled that the "equal rights of citizens" were inherent to the idea of republic. The opinion of the court from In re Duncan[49] (1891) held that the "right of the people to choose their government" is also part of the definition. Due to the 1875 and 1891 court decisions establishing basic definition, in the first version (1892) of the Pledge of Allegiance, which included the word republic, and like Article IV which refers to a Republican form of government, the basic definition of republic is implied and continues to do so in all subsequent versions, including the present edition, by virtue of its consistent inclusion.

Beyond these basic definitions the word republic has a number of other connotations. W. Paul Adams observes that republic is most often used in the United States as a synonym for state or government, but with more positive connotations than either of those terms.[50] Republicanism is often referred to as the founding ideology of the United States. Traditionally scholars believed this American republicanism was a derivation of the liberal ideologies of John Locke and others developed in Europe.

The political philosophy of republicanism initiated by Machiavelli was thought to have had little impact on the founders of the United States. In the 1960s and 1970s a revisionist school lead by the likes of Bernard Bailyn began to argue that republicanism was just as or even more important than liberalism in the creation of the United States.[51] This issue is still much disputed and scholars like Kramnick completely reject this view.[52]