Parties aren’t a built-in feature of the American political system as such—in fact, many of the people involved in setting it up were vociferous about their opposition to factionalism (and then proceeded more or less directly into some rather nasty factional conflict, because humans). The first-past-the-post decision system used in American federal elections is often cited as leading to a two-party system (Duverger’s law), and indeed probably contributes to such a state, but it’s not a hard rule; the UK for example uses FPTP voting in many contexts but isn’t polarized to the extent of the US, though it’s more polarized in turn than most continental systems.
Parties aren’t a built-in feature of the American political system as such—in fact, many of the people involved in setting it up were vociferous about their opposition to factionalism (and then proceeded more or less directly into some rather nasty factional conflict, because humans). The first-past-the-post decision system used in American federal elections is often cited as leading to a two-party system (Duverger’s law), and indeed probably contributes to such a state, but it’s not a hard rule; the UK for example uses FPTP voting in many contexts but isn’t polarized to the extent of the US, though it’s more polarized in turn than most continental systems.