Upvote:8
A key identifier (before personal IDs) was the character witness and guarantor -- someone who knew you and vouched for you. It could be done in person, or documented in an affidavit. Many documents, even today, include witnesses, attesting not only that a particular event took place (marriage, death, official acts like wills, etc), but that the parties were indeed who they said they were.
Upvote:9
The United States has traditionally been a free country, not requiring people to carry identifying documents. Even today, there are only some states that have stop and identify statutes requiring people to identify themselves when stopped on "suspicion" or for other non-criminal reasons. Even those states mostly require a person only give their name, not provide actual documentation.
Before recent times (about 1970) people in the United States were mostly known from employment records. When a person was employed a detailed investigation of their identity was generally done. This would involve questioning their "credentials" which might include letters of recommendation and a birth certificate, for example. When this was complete and satisfactory, an employee identification card was issued. Here is an example from 1906:
This card would be given to the employee and a copy would be kept by the company with their full record. For reputable companies often it would be required that a prospective employee provide multiple references from "known", responsible people essentially vouching for the person. Such documents were important to make sure that the right person was paid. Without them, a fraudster could show up on payday and try to collect someone else's paycheck.