Caruso's timbre darkened as he aged and, from 1916 onwards, he began adding heroic parts such as Samson, John of Leyden, and Eléazar to his repertoire. Caruso toured the South American nations of Argentina, Uruguay, and Brazil in 1917, and two years later performed in Mexico City. In 1920, he was paid the enormous sum of 10,000 U.S. dollars a night (~$126,000 in 2018) to sing in Havana, Cuba.
The United States had entered World War I in 1917, sending troops to Europe. Caruso did extensive charity work during the conflict, raising money for war-related patriotic causes by giving concerts and participating enthusiastically in Liberty Bond drives. The tenor had shown himself to be a shrewd businessman since arriving in America. He put a sizable proportion of his earnings from record royalties and singing fees into a range of investments. Biographer Michael Scott writes that by the end of the war in 1918, Caruso's annual income tax bill amounted to $154,000.
During his lifetime, Caruso received many orders, decorations, testimonials and other kinds of honors from monarchs, governments and miscellaneous cultural bodies of the various nations in which he sang. He was also the recipient of Italian knighthoods. In 1917, he was elected an honorary member of the Phi Mu Alpha Sinfonia, the national fraternity for men involved in music, by the fraternity's Alpha chapter of the New England Conservatory of Music in Boston. One unusual award bestowed on him was that of "Honorary Captain of the New York Police Force". In 1960, for his contribution to the recording industry, Caruso received a star located at 6625 Hollywood Boulevard on the Hollywood Walk of Fame. Caruso was posthumously awarded a Grammy Lifetime Achievement Award in 1987. On 27 February of that same year, the United States Postal Service issued a 22-cent postage stamp in his honor. He was voted into Gramophone's Hall of Fame in 2012.