They brought an extensive sugar cane farming knowledge and contributed to making the sugar industry the most important economic activity in the area. The economy reached its peak during the first quarter of the 20th century, when its sugar production enjoyed high prices on the international market as a result of the First World War.

Many Europeans settled in the city, making it a cosmopolitan center. Pan American Airlines flew its seaplanes in regularly (Eastern Macorís has the privilege of being the first Dominican city to receive seaplanes, in the Higuamo River). At about the same time the port enjoyed more commercial activity than the capital city of Santo Domingo. The next economic boom resulted in the recruitment of a large number of Afro-Caribbean workers from the Lesser Antilles. These workers and their descendants would soon comprise the majority of the population in the city and are known as the "Cocolos of San Pedro de Macoris".

When immigrants were brought in as contract labor for sugar plantations from the Eastern Caribbean they brought the sport of cricket and formed up teams. Meanwhile, the ownership and management of many of the sugar estates were American. So the cricket teams were offered money by the plantation managers to switch sports and they did. Native Dominicans picked up the game watching teams composed of Eastern Caribbeans. Over time, Vic Power established an extremely good youth system in San Pedro de Macoris and was one of the largest influences on making the city into the largest source of baseball talent in the world.