Bank of Puerto Rico. The capital used by the currency was changed from peso to dollars, giving birth to the Puerto Rican dollar. A proposal to print 1-dollar banknotes was suggested, but refused citing that it could "bring dangerous results". Series C bills were issued with a release date of "May 1, 1900" and were overstamped with "Moneda Americana" in bold red letters. They bore the signatures of the new bank governor Carlos María Soler and cashier Manuel Vicente. This marked the first and only time that currency valorized in dollars was issued outside the United States. Series E was introduced subsequently. The banknotes for this issue were bilingual, featuring the bank's name both in Spanish and English. Early specimens for Series F were produced in 1907, but they never reached circulation. The bills for this issue featured the profiles of Christopher Columbus and Juan Ponce de León. The colonial government intended to eliminate all Spanish captions from these notes, intending to accelerate a failed "Americanization" process in Puerto Rico. Series F ultimately entered circulation on July 1, 1909, still featuring bilingual captions and exhibiting a higher degree of technical quality. In 1913, the charter granted by Spain expired and the bank was closed and its assets were liquidated. After this date, Puerto Rico's economy was fully integrated into the United States' currency system, while Puerto Rican dollars were redeemed for United States dollars. Banknotes valorized in millions continued in circulation, thus a collect was ordered and held between January 16 – 24, 1916. The remaining bills, with an estimated value of $14,872 were taken out of circulation nine years later by the Puerto Rico Commercial Bank. Parallel to the Bank of Puerto Rico, American investors saw an opportunity to establish banks in Puerto Rico. The first of these was the American Colonial Bank, which opened in 1899. The establishment of national banks was proposed to the Office of the Comptroller of the Currency, with charters being eventually established in June 1900. The requirements for establishing a bank under this grant of authority, demanded that at least three-fourths of the board of directors lived in Puerto Rico at least for a year. It took the group two years to meet these regulations, but in 1902 the First National Bank of Porto Rico was inaugurated, with Andrés Crosas from San Juan serving as its president. The bank began issuing notes in