The island is unique because it is jointly administered by two nations, rather than being owned solely by France. The northern part (Saint-Martin) is an Overseas Collectivity of France, while the southern part (Sint Maarten) is a constituent country of the Kingdom of the Netherlands. This peaceful division has existed since the Treaty of Concordia in 1648, making it the only place where the French Republic and the Kingdom of the Netherlands share a land border. While there are no hard border controls between the two sides, they have different laws, currencies (the Euro on the French side and the Antillean Guilder/USD on the Dutch side), and cultures. France manages roughly 60% of the land area, while the Dutch side is more densely populated and home to the island's main international airport, Princess Juliana.