SIOUX FALLS, S.D. (AP) - Police in South Dakota's largest city say they have a seen a dramatic drop in synthetic marijuana seizures since federal raids last summer shut down the last two retail shops in Sioux Falls that sold the product.

The Argus Leader newspaper reports that officers have seized about 16 grams of synthetic dope this year, compared to 2,140 grams during the same time period last year.

Police also say seizures of real marijuana have not increased in response to the dwindling supply of synthetics.

The raids led by federal authorities last summer came two months after Gov. Dennis Daugaard signed a bill into law banning entire families of the chemicals used to make synthetic drugs.

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