The Social Register is like something between a phone book and a newspaper: its purpose is to list the addresses, deaths, marriages, etc. of the people in it. But at the same time, it has a much more important function, which is to be a signifier of elite society.

For a long time, it was fairly easy for the elite to distinguish themselves in the United States. The social pyramid contracts toward the top, and the upperest of the upper class all knew each other intimately enough that if you were in, you were in, and if you were out, you were obviously out. But over the course of the nineteenth century and the rise of new fortunes made in new industries, it became more difficult to tell who was still "that new railroad baron" (derogatory) and who had been accepted on the basis of perhaps slightly less new money or a good marriage.

The first Social Register to codify the issue by containing the people who were In and not containing the people who were Out was produced by a Louis Keller for Newport, RI, in 1886. (Newport was a seaside city where pretty much anyone who was anyone in New York City would go during at least part of the summer.) Keller went on to make a New York Social Register in 1887, and would follow it with versions for Philadelphia, Boston, Baltimore, Chicago, Washington D.C., St. Louis, Buffalo, Pittsburgh, San Francisco, Cleveland, and Cincinnati and Dayton. (Efforts to replicate it in the southeast were less successful, as high society remained a smaller circle and a published guide was unnecessary.) They were published quarterly, in order to keep up with changes of address throughout the year. In 1977, these local publications were consolidated into one larger edition.

As you can see in this November 1892 edition of the New York Social Register, the text provided was fairly lean. It's full of abbreviations to give all the necessary information. For instance, Mr. Charles Adams Appleton is "Uv. Sa. Al. Rg. Cy. '82", which the key tells me is University Club, St. Anthony Club, Aldine Club, Riding Club, and Country Club, and he graduated from a college other than Harvard, Yale, Princeton, or Columbia in 1882. (Note that the May 1893 edition doesn't have a key in it. You are expected to be a regular subscriber, or else to already have a good idea of what the clubs could be.) The Register would also list addresses (also somewhat abbreviated), maiden names, whether they were abroad ("ab'd", sometimes with a ship name), and marriage locations.

So how did people get on it? Largely by being born into it. You could also apply (and at least today, women who marry into listed families have to apply as well), but the advisory committee for applications is shrouded in mystery. It's a lot like blue checks on Twitter - if you let everyone in who wants to be there, it would lose its value. It should also be noted that an unspoken requirement has always been that you must also be white and non-Jewish. There have been a few people listed in the Register who have gotten in past this rule, but by and large it's a clear example of unstated discrimination.

And how did people get off it? In some cases they asked - John Hay "Jock" Whitney, of the prominent Whitney family (think Whitney Museum of American Art), has his listing deleted, as did George H. W. Bush before he became vice president. Largely, this is due to the optics of the discrimination issue, and some politicians have themselves reinstated in it once they retire.

Another way, more relevant here, is becoming involved with the entertainment industry. Celebrity was celebrated by people in general, but it was looked upon as gaudy and trashy by the upperest upper crust who felt above that kind of thing - it was fame-seeking, it involved people with scandals, it was not at all refined. And non-celebrities who went on the stage or sang were thought to be the kind of people who could be allowed to perform at a party but not to mingle with the guests. Charles Alden Black was in the Register before he married Shirley Temple! Even Katherine Hepburn was not allowed to be in the Register. Jane Wyatt was a descendent of the Van Rensselaer family through her mother - the family of New York state, who bought much of the land in the seventeenth century and only gave up their Dutch ways well into the eighteenth as they intermarried with the newer English elite; the mother of the Schuyler Sisters was a Van Rensselaer - and so was guaranteed a spot on it, but going on the stage was seen as such a blot against one's name to this highly exclusive crowd that she had to be removed as well.

Further reading: Privilege, Power, and Place: The Geography of the American Upper Class, by Stephen Richard Higley (1995)