Concern has been expressed that, in a free market, urban expansion in peri-urban zones tends to convert some of the best agricultural land to urban use. In many peri-urban zones of Africa, where customary tenure is juxtaposed with freehold or lease-hold tenure, this conversion is constrained by the fact that the basis to be used in evaluating expected monetary compensation in giving up land to urban developers is not clear. An example from Botswana in this paper shows that this constraint has saved the best agricultural land from being converted to urban use. The period of study is 51 years. Since 1983, the expansion of the built-up area has been redirected away from the best soils for arable agriculture, though these soils are on the main transportation routes.