The importance of USA and Canada is that its major area is covered by Prairie Grasslands.
Prairies are treeless but, the low lying plains, flowing river, valleys, woodlands can be found here.
Tall grasses, upto two metres high, could be found here which is why it is also called 'sea of grass'.
Prairies is the biggest farming region of the world. Maize, wheat, barley, rye, oats, potatoes, soyabean, cotton etc. are the major crops here. It is also known as the 'wheat basket' of the world.
Animal rearing is an important occupation in this region.