Santarem, Brazil

Lying 500 miles upriver, near the Amazon's confluence with the clear blue waters of the Rio Tapajos, Santarem has been a major river port since the glory days of the 19th century rubber boom. In the 1920s, Henry Ford carved the immense rubber plantations of Fordlandia and Belterra out of the nearby jungle. Santarem's prosperity survived the boom's eventual bust; the port lies at the heart of a region rich in natural resources, including timber and major deposits of bauxite and gold. Covering an area of some 15,000 square miles, this bustling commercial center is the third-largest city in the Brazilian Amazon with a population over 200,000.