Caucus
2 of the 6 encyclopedias on this shelf carry an entry for Caucus. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
a meeting of voters to nominate candidates for office or to name delegates to a nominating convention. In American politics a caucus is strictly a party affair. It is not considered honorable to participate in a caucus held by an opposing party, and in many states such a practice is forbidden by law. In case a United States senator is to be elected it is not unusual for the legislative members of each party to caucus, that is, meet to decide upon a candidate to be supported in formal ballot by the entire party strength. A nomination in caucus by the prevailing party is almost equivalent to an election, as all who enter a caucus are held, according to political codes, to abide by the action of that caucus. The word is first used of certain gatherings of the popular leaders of Boston under the lead of Samuel Adams, to decide upon policies and candidates for office. Thus John Adams wrote in his diary under date of February, 1753: "This day found that the Caucus Club meets at certain times in the yard of Tom Dawes, adjutant of the Boston (militia) regiment." See Samuel Adams
Collier's New Encyclopedia (1921)
in the political nomenclature of the United States, a gathering preliminary to a public meeting of citizens for election or for other purposes, generally political; a private conclave designated to influence the general body of the citizens. Also a secret preliminary meeting of the leaders of a political party to determine on a course of action, the conclusions of the Caucus being binding on all the members.
What Has Changed in the Last Century
Aiton's 1910 note that legislators "caucus" to pick a United States senator was overtaken almost at once: the Seventeenth Amendment, ratified in 1913, moved Senate elections to the voters, and the spread of direct primaries stripped the caucus of most of its nominating work, so that a caucus nomination is no longer "almost equivalent to an election." Nor are a caucus's conclusions still "binding on all the members," as Collier's wrote in 1921; in Congress the term now describes the standing party organizations — the House Democratic Caucus, the Republican Conference — whose positions members routinely break from. The one place the old sense survives is presidential nominating caucuses, above all Iowa's, which became a national fixture after 1972 before the Democrats dropped it from the front of their 2024 calendar. Both entries are otherwise sound on the Boston origin, though the John Adams diary passage about the Caucus Club is usually dated February 1763 rather than 1753.
Written for this edition, 2026.