This dissertation reexamines the economic development of Puerto Rico after annexation by the United States in 1898. I introduce new evidence in four papers exploring complementary aspects of development: public health and the mortality transition, roads and local development, patterns in regional growth, and changes in adult height. The introductory chapter provides a brief overview of recent scholarship.

The second chapter examines public health during one of the fastest mortality transitions in history and the first outside of Europe and Western offshoots. Local health departments caused most of the reduction in infant, tuberculosis, and maternal mortality from 1923 to 1945 without significantly increasing public expenditures. I present descriptive evidence that more per capita nurses and midwives, but not sanitary inspectors, correspond to larger declines in infant and maternal mortality.

The third chapter assesses the effect of roadbuilding on local economic development and regional inequality by studying the effort to connect all towns with roads. Using newly digitized maps, I show that US investments failed to reduce regional disparities. Early access to roads promoted local economic development and gave rise to path dependence in the location of economic activity, although geographic factors determined the general spatial pattern of development.

The fourth chapter describes spatial patterns in population growth from 1765 to 2010. The spatial distribution of population began to resemble the modern distribution after the turn of the 20th century, when municipal population densities diverged. Municipal population growth was positively correlated with crop production in the preindustrial era and was negatively correlated with agricultural employment from 1899 to 1970. Urbanization commenced around 1900, decades before most of the Caribbean and Central America.

The fifth chapter considers the biological standard of living in the early 20th century. Drawing on data from three surveys, I show that male height in Puerto Rico increased at more than twice the average rate for Latin America and the Caribbean between 1890 and 1940. I also show that Puerto Ricans at mid-century were among the tallest Latin Americans outside of Argentina and Uruguay. The evidence supports the conclusion that conditions improved substantially.