I never would've guessed, but according to Scientific American's Krystal D'Costa, with the advent of the binding machine in the early 19th-century -- a device that "mechanically bound grain stalks as they were cut and deposited them in neat bundles" -- the price of twine sky-rocketed due to a shortage.
The binder twine industry grew in response to the widespread adoption of the mechanical binder, linking international entities to the U.S. and Canadian harvests. Manila fiber from the Philippines, and Sisal and henequen from the Yucatan yielded twine that tied the tightest and were naturally insect repellent. Managing these materials and tools became an exercise in political identity: U.S. manufacturers produced a bevy of binder machines, but the Canadians levied heavy taxes on the imports to protect Canada' agricultural implement industry. Additionally, because the U.S. harvest occurred occurred earlier than the Canadian harvest, manufacturers sold surplus twine to Canadians but lawmakers, fearing that this arrangement placed Canada at the mercy of U.S. market, worked hard to suppress this trade with tariffs, which were meant to support Canadian production efforts instead.
Canadian farmers weren't all pleased. Some insisted that U.S. twine was superior: stronger, and more consistent in lengths. They resented the tariffs and were willing to purchase U.S. twine under the table -- and at a discount to boot. It created a black market for U.S. twine.