Which rivers form much of Paraguay's border?

Four-fifths of Paraguay's perimeter is defined by four major rivers: the Paraguay, Apa, Paraná, and Pilcomayo rivers.1

These waterways serve as significant natural boundaries for the country:

• Paraná River: Forms both the eastern and southern borders of Paraguay.1
• Paraguay River: Serves as a boundary between Brazil and Paraguay in the north and later forms part of the frontier between Argentina and Paraguay.2
• Apa River: Demarcates a portion of the border between Brazil and Paraguay.21
• Pilcomayo River: Forms the southern border of the Chaco Boreal region.1

Together, these rivers play a central role in the geography and drainage of the nation, effectively tracing the majority of its international borders.1