4. List two main factors that led the US economy to change and grow

Economic growth only comes from increasing the quality and quantity of the factors of production, which consist of four broad types: land, labor, capital, and entrepreneurship. The factors of production are the resources used in creating or manufacturing a good or service in an economy.

Geothermic gradient is the rate of increasing temperature with respect to increasing the depth in the earths interior. away from tech tonic plates boundaries, it is about 25-40 c/km (72-87 degrees f/mi) of depth near the surface in most of the world.