Cika jumla mai zuwa: Bala'o'i na halitta, ciki har da babban
girgizar kasa da tsunami a 1918 da guguwa da yawa, da kuma Babban Mawuyacin hali, sun talauta tsibirin a cikin 'yan shekarun farko a ƙarƙashin mulkin Amurka. Wasu shugabannin siyasa, kamar Pedro Albizu Campos, wanda ya jagoranci Jam'iyyar Nationalist ta Puerto Rican, sun bukaci canji a dangantakar da Amurka. Ya shirya zanga-zanga a Jami'ar Puerto Rico a shekarar 1935, inda 'yan sanda suka kashe mutane hudu.