Things changed in 1850. Everyone was counted by name, address, age, sex, color (white, black or mulatto) if they were deaf and dumb, blind, insane or idiotic, the value of the real estate they owned, their occupation, place of birth, if they were married that year, attending school that year, unable to read or write if they were over 20, and if they were either a pauper or convict.
The same questions were asked in 1860 and 1870. In 1870 Chinese and Indian were finally allowed to be counted. Also counted was citizenship for males over 21.
In 1880 everything changed. The census was divided into five parts: Population, Mortality, Agriculture, Manufacturing, and Social Statistics. The process took 7 years to complete.
The 1890 census changed many things. It was also destroyed by fire in 1921. The following questions were asked including name, address, gender, age, marital status, married within the year, number of families in house, number of persons in house, whether a soldier, sailor or marine (Union or Confederate) during Civil War, or widow of such person, relationship to head of family, race, described as white, black, mulatto, quadroon, octoroon, Chinese, Japanese, or Indian, mother of how many children, and number now living, place of birth of person, and their father and mother, if foreign born, number of years in US, whether naturalized, whether papers have been taken out.
Also asked were profession, months unemployed during census year, ability to read and write, ability to speak English, and, if unable, language or dialect spoken, whether suffering from acute or chronic disease, with name of disease and length of time afflicted.
Was the person defective in mind, sight, hearing or speech, or whether crippled, maimed or deformed, with name of defect, whether a prisoner, convict, homeless child, or pauper, home rented, or owned by head or member of family, and, if owned, whether free from mortgage, if farmer, whether farm is rented, or owned by head or member of family; if owned, whether free from mortgage; if rented, post office box of owner.
In 1900 the process was simplified to name, address, relationship to head of family, sex, race, age, marital status, number of years married, number of children born to women, immigration, months not employed, education, ability to speak English, if on a farm, and did they rent or own their home.
Basically the same questions were asked in 1910 and 1920, along if naturalized, mother tongue of person and parents, year of immigration, blind, deaf or dumb, and if they were a survivor of the Union or Confederate Armies.