Border rivers are rivers that form part of the boundary between two countries or regions. They often serve as natural barriers and can influence political, economic, and social interactions between neighboring areas. Examples of border rivers include the Rio Grande between the United States and Mexico and the Danube which flows through several countries in Europe. These rivers can be vital for trade, transportation, and resource sharing. They may also be subject to treaties and agreements to manage water usage and environmental protection. The management of border rivers often requires cooperation between the countries they separate to ensure sustainable use and conflict resolution.