Ten Days in Kenya With No Cash, Only a Phone

Graeber traveled from New York to Nairobi to learn how to pay for things with a phone -- and to understand why Kenya has gained a reputation as the mobile payments future.

Almost everyone in the country uses M-pesa (M, for mobile; pesa is payment in Swahili) to transfer money from one phone to another via encrypted short message service, or SMS. In all, there are about 18.2 million active customers in a nation twice the size of Colorado.