|There really is no such thing as an average US or Canadian tree owing to the extent of the land. Many more elements have to be considered than for the UK: such as altitude; temperature; and especially the type of soil including moisture content; terrain eg canyons, flatlands and swamps.
A typical hardwood forest is about 85 feet tall and a large stand alone hardwood tree may reach a height of 110 - 120 feet. However obviously there are several both larger and smaller than these.
Not all forest tree species grow equally well throughout the US. Native forest trees of a species have certain biological constraints that confine them naturally to forest regions or types. These natural collections of tree species are called 'forest types'.
A forest type is a classification of forest land based on the species presently forming a plurality of living trees growing in that particular forest.