One of the defining features of modern american politics is the division between the two major parties on most policy issues, with little crossover. this is known as party

The correct answer is polarization

Polarization is basically that there's one side and there's the other side and the mindset between them is that you're either with them or against them. George Washington wanted to prevent this which is why he had his speech against parties, but nobody listened and now the society is extremely polarized.