Hey!
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The map that is given gives you a hint to what the answer is. On the legend it states the hint, "people per km²". This tells us that the map shows the population density in South America. A population density map shows which areas have the most people to least people.
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Hope This Helped! Good Luck!
Answer:
it's called Rio Grande del Norte (it's also the 5th longest river in North America and ranking 20th for the longest river in the world)
hope that helps!!
Your answer will be show patriotism