This term, in political parlance, means any arrangement by which a party makes sure of a certain addition to its legitimate strength in the hour of trial--that is, the election. In other words, to lay pipe means to bring up voters not legally qualified.
It were too long a story to tell the origin of the term at length. In brief, it arose from an accusation brought against the Whig party of this city (New York) some years ago, of a gigantic scheme to bring on voters from Philadelphia. The accusation was made by a notorious Democrat, of not very pure political character, who professed to have derived his information from the agent employed by the Whigs for the service. This agent had actually been employed by certain leaders of the Whig party, but on a service deemed legitimate and proper in the art of electioneering. He, however, turned traitor, and, as was alleged by the Whigs, concocted a plot with the notorious Democrat to throw odium upon the Whigs. A mass of correspondence was brought forward in proof, consisting mainly of letters written by the agent to various parties in New York, apparently describing the progress and success of his operations. In these letters, as if for the purpose of concealment, the form of a mere business correspondence was adopted--the number of men hired to visit New York and vote, being spoken of as so many yards of pipe--the work of laying down pipe for the Croton water being at that time in full activity.
The Whig leaders were indicted, on the strength of these pseudo revelations, and the letters were read in court; bu[t] the jury believed neither in them nor in the writer of them, and the accused were acquitted.
The term pipe-laying," however, was at once adopted as a synonym for negotiations to procure fraudulent votes.--[J. Inman.]