The tenement houses built to accommodate the influx of foreign immigrants and rural migrants were usually ill equipped to handle basic sanitary needs.  Latrines and outhouses emptied into yards and streets, while the city's drainage system was designed for surface water, not sewage.  When the municipal government awarded contracts for street cleaning and other city services based on political considerations, the results were neglect and inefficiency.  Up to 30,000 horses, the major mode of urban transit, packed waste into the narrow cobblestone streets.  Blood flowed into the streets from the slaughterhouses, while tanning yards emitted a powerful stench.  The putrid atmosphere was so bad during the humid summer months that residents who could leave the city generally did so.

In 1865, the Citizens' Association, a "good government" reform organization, sought to circumvent the city's Democratic machine and appeal to the public and the Republican-controlled state administration.  The Citizens' Association produced a landmark, 20-volume study of sanitation in the entire city, which it condensed to a 500-page document.  As incidents of cholera and small pox threatened to become city-wide epidemics, Harper's Weekly and other newspapers reported the group's findings to gain support for the Metropolitan Health Bill.  The proposed legislation was drafted by Dorman Eaton, a prominent civic reformer and chairman of the Citizens' Association's legal committee.  In April 1865 (shortly after this cartoon appeared) the bill passed the New York senate, with a 17-6 majority consisting of all 16 Republicans and one Democrat who was a physician.  The bill met defeat, though, in the assembly, 60-52.  

Public interest in the legislation revived when news reached the United States of a cholera epidemic in Europe.  It was expected that, as in the past, the disease would arrive on American shores within a few months or a year.  The press kept the public updated on the transmission of the disease across Europe; it hit England and France in the late summer of 1865.  During the fall election season, campaign coverage had to compete for headlines with news of the approaching cholera epidemic.  

In the fall of 1865, Republicans gained seats in both houses, with the radical faction making a strong showing.  In his annual message, Governor Reuben Fenton emphasized the health crisis and urged passage of the bill.  The final version of the measure included a commission consisting of the four police commissioners, the health officer of the Port of New York, as well as four commissioners appointed by the governor, three of whom were required to be physicians.  On February 19, 1866, the bill passed the New York senate, 22-2, and the assembly, 74-28, and was signed into law by Governor Fenton on February 26.

Governor Fenton's appointments to the new Metropolitan Board of Health were generally praised, and they set about their task with vigor.  Within a few weeks, they secured an agreement with city butchers to clean up and eventually relocate their slaughterhouses.  Health standards were imposed on the milk industry, the water supply was improved, and city streets even began to be cleaned, with the removal of thousands of tons of horse manure.  When the cholera epidemic broke out later in the spring of 1866, the Board of Health fought it with a stringent health code, house to house inspections, disinfectants, and quarantines.  Although the Democratic New York World charges the board with "terrorism," the death toll in New York City was kept under 500, compared with 1200 in Cincinnati and 3500 in St. Louis.  With its short-term success, the New York Board of Health served as a model adopted by other cities and states.