Methodological note :

This data was culled from the original U.S. census manuscripts, as found on www.ancestry.com. Jews are understood to constitute an ethnic group of Eastern and Central European origin characterized by common names and occupational pursuits, as well as a distinctive language. This definition lends itself well to analysis of the data preserved in census records.

Two primary methods were used to identify Jews:

1. Individuals born abroad whose mother tongue is "Yiddish," "Jewish," or "Hebrew" were automatically included in the spreadsheet, as were all members of their families.

2. For individuals born abroad whose mother tongue was another Eastern or Central European language (e.g., Russian, Polish, German), or individuals born in the U.S. with one or more parents from Eastern or Central Europe, we examined surnames, given names within a household, and occupations in light of common Jewish characteristics. This method of analysis is, of course, subject to inaccuracy, as we may have excluded Jews with uncommon names or occupations or included non-Jews whose characteristics appear Jewish. Individuals listed with the annotation "nj?" in the far right-hand column are those whose Jewish ancestry is plausible but questionable.

This method of analysis easily misses Jewish households whose members' parents were all born in the United States. In 1930 Maine, however, such households were quite rare. Special efforts were made to identify households of this nature in Portland, where they constituted less than 1% of identified Jewish households.

All members of a household containing a Jew are included in the spreadsheet, with the exception of Jewish lodgers and servants, who are listed individually. Household members who are evidently not Jewish (such as non-Jewish servants and some spouses or in-laws) are listed with the annotation "nj."