A once-remote patch of rainforest is now packed with migrants trying to reach the U.S.

DARIEN JUNGLE, Colombia – For centuries, jungle-covered mountains, swamps and poisonous snakes scared people away from the Darién Gap, the dense rainforest separating North and South America. It's still the only spot where the Pan-American Highway, that runs from Alaska all the way to the tip of South America, dissolves into mud.

But thanks to the large numbers of migrants trying to get to the United States, the Darién Gap is no longer a no man's land.

In fact, when NPR first reached the region in September, birds singing and monkeys howling could not be heard. The