France’s longest land border is in South America
Brazil shares the longest physical land border with France. The reason is French Guiana: a region on the northeastern coast of South America that is an integral part of France, not an independent country. Its borders count as French national borders even though they are thousands of miles from Paris.
That makes the France–Brazil boundary longer than France’s land borders with neighboring European countries such as Spain. The answer depends on looking beyond metropolitan France—the familiar part of the country in Europe—to include its overseas territory.
A river marks much of the boundary
Much of the frontier follows the Oyapock River, through a sparsely settled stretch of tropical forest. The river is both a natural boundary and a route through a region where roads are limited, so crossing between the two countries has long been more complicated than simply driving across a line on a map.
A bridge links the Brazilian town of Oiapoque with Saint-Georges in French Guiana. It gives the remote border a strikingly ordinary feature: a road crossing between Brazil and France, on opposite sides of a South American river.
