Dear Ms. Hodges,
Thank you for posting your request on History Hub!
The decennial census was a federal function and was not the responsibility of states, although some states had their own censuses separate from the federal census. The censuses captured information about the populace as of a given date in the census year. The U.S. Census Bureau did not track name changes or movements of persons in between census. Instructions for conducting the 1890 Census may be located on the website of the U.S. Census Bureau. Most of the 1890 census records were destroyed in a 1921 fire. See NARA’s web page on Census Records for more information about federal census records. Please contact the applicable state archives for information about state census records.
For questions about the 19th laws and regulations regarding public health, please contact the state and, if applicable, municipal or county archives of the localities in which you are researching. They also may be able to provide information about the location of any death records, however please note that the practice of registering deaths did not exist throughout much of the 19th century. For example, in Alabama, statewide registration of deaths did not begin until 1908, though for earlier times probate court records are sometimes available.
The National Institute of Health (NIH) Library also may be able to assist you in researching historic medical practices. And Historic Saranac Lake has collections relating to the the Trudeau Sanatorium in New York and may be able to provide insights into the practices of the time
Since official name changes were conducted through a legal process, there may be records in local courts. In many jurisdictions, county and other local court records are maintained by the clerk of court. If someone simply started using an alias, there may not be a government record of that fact.
Railroad companies may have kept cargo manifests, however the exact contents of these records and how long they were retained varied from company to company. Such corporate records that have been preserved from that time period are spread between a wide variety of libraries, museums and other such institutions. You would need to know which company was involved and then search for an institution with records of that company.
We hope this information is helpful. Best of luck with your research!