Why is the US said to have a two party system?

Answer 1

The battle over ratifying the Constitution resulted in the formation of two political parties.

Answer 2

Basically, it is because of the way elections are decided. In the United States, districts are single-member (they only elect one member) and first-past-the-post (the winner takes the seat based on achieving a plurality of votes). Because of this configuration, the system conforms to Duverger's Law, which roughly specifies that the number of viable parties in a first-past-the-post system is n+1, where n is the number of members elected in a given district (in the US n = 1, and so 1+1=2 viable parties).

Answer 3

It is largely tradition, also third parties often have a hard time "breaking in" until one of the existing parties begins to decline or a major political crisis is happening (e.g. the Republican party and the Slavery/Abolition issue).

Answer 4

Because it keeps the people who are in power in power. It appears to be fair and competitive while fooling people into thinking representative democracy works.

Answer 5

Because there are two major parties in the USA: the Democratic and the Republican (although people are free to organise or join any other parties).

Answer 6

It doesn't have to have a two party system. It could have three or four but the politicians have found that they do best with two.