The Midwest is the biggest agricultural region in the United States, and of the biggest in the world. It is a region that has specialized in the production of several crops that are highly demanded on the market, and are used for multiple different things.
The reason why the Midwest has became an agricultural center is that it has very deep and highly fertile soil. The soil is of such a good quality because naturally this region is a grassland, so the enormous amounts of decaying grasses have created a very good soil suitable for growing numerous types of plants.
Unfortunately, converting the region into an agricultural center has caused lot of environmental problems. The grasslands have mostly been destroyed, and with it the habitat of lot of animals. The extensive usage of pesticides and other chemicals has resulted in pollution of the waters. The mechanization used in the agriculture has become one of the major contributors to the greenhouse gases emissions. Because big portion of the region is semi-arid, or only gets sufficient amounts of rainfall seasonally, the aquifers have been depleted.
B.) Forestry and Mining because it is a great source for metals and minerals such as copper, gold, iron, nicklel, uranium, zinc, and silver.
A change in the core would have the greatest effect on the convection currents in the mantle. Hope this helped!
Geography affects trade because depending on the features of the geography (enviroment), it also affects the "system" of trading and also the type and amount of supply that is coming in. It can aslo affect who you're trading with.
For an example, if your enviroment has little to no water, how will you trade by ship? You can't, so you go with a different system such as trading that substitues land.
Long answer but hope this helped :).
