Britain's primary overseas interests lay in three areas: Europe, the former British Empire or Commonwealth, and its special relationship with the United States. The British Empire encompassed many countries that gained independence starting in the late 1940s. The modern Commonwealth is now a voluntary association of 54 independent states. Britain has close historical, cultural, economic and personal ties to many former colonies. Britain's relationship with Europe has also been influential, and over half of its trade is now with European Union countries, of which Britain has been a member since 1973. The European Union aims to promote integration between member states. Britain maintains a special relationship with the United States based on shared language, culture, history and security interests.