Ten medical marijuana dispensaries have complied with letters sent by U.S. Attorney John Walsh to shut down, the U.S. Attorney's office confirmed in a press statement Tuesday. The dispensaries were within 1,000 feet of schools and were notified in early August that they had 45 days to shut down, move their business or face federal enforcement action.

According to 7News, the 10 shops that got the letters were in the Denver metro area and in southern Colorado.

This is the third wave of letters Walsh has sent out to Colorado dispensares deemed too close to schools. Walsh's actions have resulted in a total of 57 medical marijuana dispensaries that have now been shuttered since the crackdown began in January in what has become the most aggressive law-enforcement action against the medical marijuana industry that the federal government has pursued in the state.

And the crackdown will not be ending anytime soon it appears. In a press release, Walsh's office said that a fourth wave of letters is forthcoming as additional marijuana shops are identified within this 1,000 foot “drug-free school zone.”

Walsh's office cites the Controlled Substances Act, title 21, section 860, a federal law which references the 1,000 foot boundary for manufacturing or distributing a controlled substance near a school or college, although nothing in Colorado's medical marijuana law specifies the distance between a shop and a school, the decision, like most such zoning matters, is left to local communities.

"I can see no legitimate basis in this judicial district to focus the resources of the United States government on the medical marijuana dispensaries that are otherwise compliant with Colorado law or local regulation," Boulder District Attorney Stan Garnett told Walsh in a recent letter. "The people of Boulder County do not need Washington, D.C., or the federal government dictating how far dispensaries should be from schools, or other fine points of local land use law.”

However, Walsh is dedicated to this crackdown. In a copy of a letter responding to Garnett obtained by The Denver Post in March, Walsh reiterated his intent to close all dispensaries operating within 1,000 feet of a school, and noted that these closures are "not at the direction of Washington, D.C., but [at Walsh's direction] as U.S. Attorney and as a Coloradan."

While the feds crackdown on medical marijuana, Coloradans are getting ready to vote on Amendment 64 and will decide whether Colorado should legalize marijuana this November.

Amendment 64 seeks legalization and regulation of marijuana for recreational use for adults and appears to be quite popular amongst Colorado voters. Several recent polls show that a strong majority of Coloradans favor the ballot measure.

Below, where you can find legalized medical marijuana in the United States:

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  • Alaska

    Legalized for medical use. <a href="http://www.flickr.com/photos/alanasise/6847095796/" target="_hplink">Flickr: alana sise</a>

  • Arizona

    Legalized for medical use. <a href="http://www.flickr.com/photos/billward/110338154/" target="_hplink">Flickr: Bill Ward's Brickpile</a>

  • California

    Legalized for medical use. <a href="http://www.flickr.com/photos/gerbache/2260207829/" target="_hplink">Flickr: gerbache</a>

  • Colorado

    Also legalized possession by non-medical users. <a href="http://www.flickr.com/photos/dok1/520845832/" target="_hplink">Flickr: dok1</a>

  • Connecticut

    Legalized for medical use.

  • District Of Columbia

    Legalized for medical use. <a href="http://www.flickr.com/photos/bigberto/2770838680/" target="_hplink">Flickr: ~MVI~ (off to coron)</a>

  • Delaware

    Legalized for medical use. Flickr: <a href="http://www.flickr.com/photos/dougtone/7749689644/">Doug Kerr</a>

  • Hawaii

    Legalized for medical use. <a href="http://www.flickr.com/photos/ricardo_mangual/6006230817/" target="_hplink">Flickr: Ricymar Fine Art Photography</a>

  • Illinois

    Legalized for medical use.

  • Maine

    Legalized for medical use. <a href="www.flickr.com/photos/indywriter/2683524563/" target="_hplink">Flickr: indywriter</a>

  • Maryland

    Legalized for medical use.

  • Massachusetts

    Passed ballot initiative for legalized medical marijuana in 2012.

  • Michigan

    Legalized for medical use. <a href="http://www.flickr.com/photos/kayoticblue/213316452/" target="_hplink">Flickr: ckay</a>

  • Montana

    Legalized for medical use. <a href="http://www.flickr.com/photos/csbarnhill/2633187564/" target="_hplink">Flickr: csbarnhill</a>

  • Nevada

    Legalized for medical use. <a href="http://www.flickr.com/photos/http2007/4699361533/" target="_hplink">Flickr: http2007</a>

  • New Hampshire

    Legalized for medical use.

  • New Jersey

    Legalized for medical use. <a href="http://www.flickr.com/photos/paulflannery/4021996652/" target="_hplink">Flickr: psflannery</a>

  • New Mexico

    Legalized for medical use. <a href="http://www.flickr.com/photos/everyskyline/3134662783/" target="_hplink">Flickr: michaelwhitney</a>

  • Oregon

    Legalized for medical use. <a href="http://www.flickr.com/photos/d-powell/2099638403/" target="_hplink">Flickr: digging90650</a>

  • Rhode Island

    Legalized for medical use. Also decriminalized possession of less than one ounce.

  • Vermont

    Legalized for medical use. <a href="http://www.flickr.com/photos/bryanalexander/6129117/" target="_hplink">Flickr: BryanAlexander</a>

  • Washington

    Legalized for medical use. Also legalized possession by non-medical users. <a href="http://www.flickr.com/photos/rose_braverman/6924724331/sizes/l/in/photostream/" target="_hplink">Flickr: Rose Braverman</a>