It said the driver, who was not identified, was deemed inadmissible into the U.S., and escorted back to Canada. The truck was impounded, and a $5,000 penalty was assessed.
The agency said the truck was referred to a secondary inspection after an X-ray scan yielded “results inconsistent with the purported goods”.
It said a subsequent physical inspection conducted by officers and a canine unit revealed 205 kg of the drug, concealed in 13 cartons among the legitimate cargo.
An additional quantity of THC gummies for personal use was recovered from the cab of the tractor, the agency said.
THC, or tetrahydrocannabinol, is the main psychoactive compound in cannabis.
The Detroit Field Office, which covers all ports of entry throughout Michigan, has seen a significant increase in illicit drug seizures since travel restrictions were imposed in March to stop the spread of Covid-19.
This year, the office has seized more than 5 tons of marijuana at ports of entry across the state.
In Washington, the House of Representatives voted Friday to remove marijuana from the federal schedule of controlled substances.
The bill will now head to the Senate, where it is unlikely to pass.