When South American navies outgunned the United States

Could Chile and Brazil outgun the United States Navy from the 1870s into the early 1890s?

Yes. Chile had more naval firepower, and Brazil's advantage was greater, creating concern among US politicians for about two decades.

South American naval strength exceeded that of the United States for part of the period after the American Civil War. The comparison runs from roughly 1872 to the early 1890s, when US congressmen had reason to worry about the balance of firepower. Chile could field more naval firepower than the United States, and Brazil presented an even stronger case. A viewer points to new South American ironclads and protected cruisers, including the Chilean battleship Capitán Prat, as examples of that wider naval strength. The exchange corrects the assumption that the United States already possessed uncontested hemispheric sea power throughout the late nineteenth century.