Statistics for occurrence #1 of “Porto Rico” in chapter 1 of George Bancroft, History of the United States from the Discovery of the American Continent, Vol. 5, 13th edition.:

...uth America, except Brazil and the Guianas; all Mexico and Central America; California, which had no bounds on the north; Louisiana, which came to the Mississippi, and near its mouth beyond it; Cuba, Porto Rico , and part of Hayti; and mid-way between the Pacific and the Indian Ocean, the Marianna and Philippine groups of isles; in a word, the countries richest in soil, natural products, and mines, and havin...
Max. Freq. Min. Freq.
Entity Corpus Doc Corpus Doc  
Porto Rico 596 4 0 0 0 user votes
Porto Rico (Angola) 0 0 0 0 0 user votes
Porto Rico (West Virginia, United States) 0 0 0 0 0 user votes

† This entity has been selected by the automated classifier as the most likely match in this context. It may or may not be the correct match.