"Pipe layer" is of only historical interest today.
15 December 1840, Republican Compiler (Gettysburg, PA), pg. 3:
From the Detroit Daily Free Press.
THE "PIPE LAYERS."
Almost every letter we get from the interior of this State tends to convince us that the Bank party have had their "pipe layers" in Michigan as well as in other States. One friend writes us thus:
"No less than thirty or forty strangers, unknown to any of us, swore in their votes here."
19 December 1840, Milwaukee (WI) Advertiser, pg. 3:
And here (Philadelphia - ed.), a clinque of wealthy men club together and collect a capital of $7000 or $8000, which they employ and spend in one solitary operation of "pipe laying."
March 1841, Radical, in Continuation of Working Man's Advocate, pg. 39:
I have very little doubt that on a direct vote of the whole people for a President, instead of a part as in Rhode Island and New Jersey, and on one day throughout the Union, so as to avoid "pipe-laying," Mr. Harrison would not have had it in his powerr to stand up in the Capitol and tell the people that a majority of them had sanctioned violations of the constitution.
29 May 1841, The New-Yorker, pg. 169:
The Trial of J. B. Glentworth for alleged "pipe-laying" and introducing illegal voters in the Elections of Nov. 1838, and April, 1839, is proceeding in our Court of Sessions as we go to press.