As of now, 20 states have legalized marijuana for medical purposes, and voters in Colorado and Washington have approved marijuana for recreational use. About a dozen more states are expected to legalize marijuana in some form over the next several years.
As of January 31, 2014, passengers traveling internationally into the U.S. and connecting to another flight are allowed to have in their carry-on baggage liquids in excess of 3.4 ounces (100 mL) that were purchased as duty-free merchandise.
If the container is small (a capacity less than 3.4 fluid ounces or 100 ml) you can bring as many as you want in your carry on bag. If the container is larger than 3.4 fluid ounces (100 ml), you may not be able to bring it through security.