With his growing credibility in the medical field, Billings oversaw work done to aid those struggling with yellow fever.

[5] In 1843, Billings' family moved to Rhode Island, but in 1848 returned to Allensville, Indiana due to his father's relocation as a postmaster.

Due to his love for learning and education, he agreed to renounce any inheritance if his father allowed him to attend college.

[5] His thesis, The Surgical Treatment of Epilepsy, drew attention from the faculty as an accurate description of the operations implemented at the time.

After serving as the executive officer at the hospital for several months, he was directed to the Army of the Potomac in March 1863 and was assigned to Sykes' Division of Meade's Corps in the 11th Infantry Regiment.

Billings also recruited a young man named Harry Miller Lydenberg to work as his personal assistant and head of reference.

[11] Billings was the senior editor of books reporting the work of the Committee of Fifty to Investigate the Liquor Problem in the early 1900s.

He took European ideas of ventilation and applied them in the context of the hospital's environment, which was a crucial factor to consider in light of Baltimore's varying weather.

By hiring the right people, Billings believed a lot of medical errors could be avoided, thus improving the efficacy of the hospital.

[11] Billings served as the primary advisor to Gilman, in charge of engineering and implementing the initial educational infrastructure of Johns Hopkins School of Medicine.

Department chairs of the medical school were jointly the heads of services at the Hopkins hospital, allowing both organizations to benefit from their expertise.

Billings also played a significant role in the determination of the philosophy, structure, organization, and faculty of the Johns Hopkins Medical School.

[17] Billings emphasized Hopkins' Medical School's unique location in Baltimore as something to be taken fully advantage of, knowing its potential for research about illnesses as well as the capacity to treat them effectively.

[17] Between 1869 and 1874, Billings was asked by the Secretary of the Treasury to inspect and report upon the hygienic conditions of the Marine Hospital Service.

With this appointment, Billings was required to travel across the United States in order to inspect and provide recommendations for improving the sanitations policies of the hospitals.

This became known as the Public Health Service, which is the branch of government that works with the medical personnel of the Army and Navy to further preventive medicine.

[18] In 1879, Billings with Dr. Charles F. Folsom, Colonel George E. Waring, Jr., and other members of the National Board of Health surveyed citizens of Memphis, Tennessee, in order to gather data regarding the outbreak of yellow fever in the city.

His recommendations to the city board members regarding the sanitation policies were described as a "miracle tonic" by local newspapers as yellow fever cases dropped following his visit.

[19] Billings figured out how to analyze medical and demographic data mechanically by turning it into numbers and punching onto cardboard cards as developed by his assistant at the Census Office, Herman Hollerith.

[27][28] His portrait,[29] painted by Cecilia Beaux, hangs in the Main Reading Room of the U.S. National Library of Medicine, where several collections of his papers are located.