Most of it is done in Africa and South America, Brazil, etc. 

Ford use to have several rubber plantations but got out of the business. Firestone and Goodyear hold the largest rubber plantations in the world. 

Most of Brazils wealth came from the boom of cars and rubber products from the USA in the early 1900's. 

Today most rubber is scientifically made with resins and polymers but some items are still made with 100% pure rubber. 

It comes out of a tree like plant much like maple syrup does. You slice the tree on an angle just deep enough for the sap to come out but not deep enough to harm the tree.

Hope this helps:)