City Directories provide names and occupations of town residents and much local business information.
The National Archives and Records Administration (NARA) in Washington, DC and its Regional Branches, is the principal repository for records relating to the US federal government. These include the original paper copies of the federal census, all pre-World War I military records, Native American records, military service and pension records, naturalization records, ship passenger lists, land-entry case files, and homestead and bounty land warrant records. NARA's website is the place to begin research for federal records.
Birth Records can be difficult to obtain because they can be used for so many purposes. You may be required to provide proof of relationship and proof of the person's death.
The 1880 census was the first to identify the relationship between the household member and the head of house.
Remember to document everything you find on your ancestors. Undocumented genealogy is mythology!