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.
A. These substances are exempt from the rules above. As long as you declare them at the security checkpoint, you may carry more than 3.4 ounces, and they do not need to be placed in a plastic bag.