That's a good question, and I've been trying for weeks to find the answer. 132 columns for printers is way older than video terminals, dating back to the IBM 14

That's a good question, and I've been trying for weeks to find the answer. 132 columns for printers is way older than video terminals, dating back to the IBM 1403 printer from 1959. I've studied the 1403 printer closely and asked the IBM history experts, but nobody seems to know exactly where 132 columns came from. One theory is IBM wanted to have more columns than competitors with 120 columns, so went to 132, but that's not a completely satisfying answer. I wonder if 132 is a limit due to the (surprisingly complex) timing of the print chain, but haven't been able to nail it down. I've studied the 1403 printer's circuitry in detail, and haven't seen any reason for 132 columns. If the printer had 12 characters per inch, 11 inch wide paper would have 132 characters, but the printer has 10 characters per inch so that doesn't explain it.