This paper looks at how the installation of sewers, food hygiene regulations, and trash reform affected mortality from infectious diseases in Brooklyn and Manhattan from 1867 to 1927 combining data from Historical Urban Ecological dataset, the census and Brooklyn and New York Departments of Health. A linear regression with fixed effects is used to investigate which diseases these policy decisions impacted the most. The results will show that milk sanitation, a food hygiene regulation, had the greatest effect on reducing infectious diseases. Installing sewers had a beneficial effect on Manhattan, but Brooklyn saw an increase in infectious diseases as sewage from Manhattan was dumped upstream of Brooklyn. Similarly, trash reform in Manhattan worsened the health of people living in Brooklyn because trash from Manhattan was burned in Brooklyn. These results may guide policy-makers in developing countries to prioritize food safety regulations as well as sanitation of waste over relocation to minimize negative externalities.