Why is the street curve?

Question

why isn't the street flat?

Answer 1

It's called a crown and allows water to drain toward each side of the road (or a center drain on a divided highway) where storm drains and conduits carry it way from the road.  Car wheels are typically aligned (in the US) with the right front wheel set slightly forward of the left to compensate for the tendency of a vehicle to drift toward the lower portion of the paved surface.  

Answer 2

It's called camber and it is for water to run to the side of the road.

Answer 3

Yup. exactly. So that rain water and snow dont create a lake in the road.. so that the water can collect in the gutters then into the sewers.

Answer 4

So rainwater doesn't pool on it.