Of course, the majority of Americans are right, and the majority of American are left, and the majority of American are also centrist, depending how you define left, centre, and right. So unless one adopts a set of definitions, and does some major polling, the most accurate, stable statement, IMHO, would be that Americans are pretty equally right (= Republican) and left (=  Democrat). 

The spectrum is more fluid here in Canada and in the UK and in continental Europe, as expressed my multi-party options with more fluid boundaries than in the US.

BTW, Tridentinus, did I hear correctly that you Brits are currently flirting with alternate voting systems like proportional representation?