Based on suggestions of local indigenous rubber workers who were familiar with the area, he began an initial exploration and subsequent clearing of the isthmus for trade.

[2] The land bridge has a slow upward slope and features one 500-metre hill with a 74% gradient in its middle; mules were used to carry cargo across that inconvenient dirt road (a "trocha" in Spanish).

Once completed, the Isthmus of Fitzcarrald and the routes which came after it, connected the Madre de Dios basin to the west coast of Peru.

Rubber collectors in the region could send their product Puerto Maldonado, situated between the Tambopata and Madre de Dios rivers.

With rubber no longer needing to be shipped, the isthmus route grew over again and is invisible on satellite images as of 2019 – only the two rivers remain visually.