1950 Industry classifications in earlier censuses

Industry (code) of employment is available for the 1900 census (and other early censuses) using 1950 industry classifications. However, there are some industries that were common in early periods (and appear in the aggregate documentation of the 1900 census) that no longer exist in the 1950 classification. Example: manufacturing of cariages and wagons. Is there any way to get the original classifications of these data?

This is a good question. As discussed on the comparability tab for the IND1950 variable: Industry was first asked as a distinct question in the 1910 census. For earlier samples, industry is inferred from occupation responses (recorded in OCC). Often, the industry was unambiguous since many respondents report their industry rather than their occupation to the occupation question. So, the original classifications for IND1950 for these early census files can be found in the OCC variable.