Bangladesh, Sept. 28 -- The African Continental Free Trade Area represents one of the most ambitious economic integration projects attempted anywhere in the world. Designed to create a single African market for goods and services, the agreement promises to reduce trade barriers, strengthen regional supply chains and make it easier for African businesses to sell across national borders.

But the ultimate success of continental free trade may depend less on Africa's largest corporations than on its smallest traders.

Across the continent, millions of people make a living moving relatively small quantities of food, clothing, household products and other goods between neighboring countries. Much of this commerce takes place outside conventio...