When in history did the use of Sr and Jr start for defining father and son with same name?

The use of "Sr." (Senior) and "Jr." (Junior) to distinguish between a father and son with the same name began in the United States in the late 19th century. This practice became more formalized in the early 20th century, as naming conventions evolved within American society. While the specific origins are difficult to pinpoint, it reflects a broader trend of family lineage and identity in naming practices during that time.