Understanding the laws surrounding cannabis and travel has become increasingly important as more states continue to legalize medical or adult-use marijuana. While legalization has expanded rapidly across the United States, the rules governing transportation remain complex. Travelers often assume that driving or flying with cannabis is straightforward once they are in a legal state. In reality, laws differ significantly between states, jurisdictions, and federal authorities, making preparation essential. According to guidance from the Transportation Security Administration (TSA) and state regulatory agencies, cannabis remains illegal at the federal level, creating unique challenges for travelers navigating airports, highways, and borders.

One of the most important principles is that federal law governs air travel. TSA officials do not actively search for cannabis, but they are required to report suspected violations of federal law. While hemp-derived products containing less than 0.3% THC are federally legal under the 2018 Farm Bill, marijuana remains a Schedule I drug. As noted by TSA public guidance, local airport police typically determine how to proceed when cannabis is discovered, and outcomes vary widely depending on the state. In adult-use states like Nevada, Colorado, and California, police may simply ask passengers to discard the product. In contrast, travelers flying out of states without legalization may face fines or more serious consequences.

Driving with cannabis demands a separate set of considerations. State lines remain legal boundaries, and crossing them with marijuana—whether purchased legally or for medical use—is prohibited under federal law. Even between two legal states, transporting cannabis across state borders is technically illegal. State highway patrol agencies, including those in Oregon and Washington, continually remind drivers that possession is only protected within state boundaries. Additionally, impaired driving laws apply nationwide. Every state enforces prohibitions on driving under the influence of cannabis, and penalties can mirror or exceed those associated with alcohol impairment.

Medical patients face additional complexities. Although more than 35 states have medical marijuana programs, medical reciprocity varies. A handful of states—including Nevada, Arkansas, and Maine—recognize certain out-of-state medical cards, but most do not. The National Conference of State Legislatures (NCSL) highlights that medical patients must follow the rules of the state they are entering, regardless of home-state authorization. This means possession limits, allowable product types, and consumption rules may differ significantly from what patients are used to.

International travel adds another layer of strict regulation. Most countries, including Canada and Mexico, prohibit crossing borders with cannabis regardless of whether the traveler is departing from or entering a legal jurisdiction. Canadian Border Services Agency (CBSA) guidance states that carrying cannabis across the border without authorization is a serious criminal offense. The same applies when entering or leaving the United States, where federal law controls all ports of entry.

For travelers, the safest strategy is to understand and follow local and federal rules, avoid transporting cannabis across borders or state lines, and purchase what they need only after arriving at their destination in a legal jurisdiction. Researching local laws, airport rules, and state possession limits can help ensure a smooth and compliant travel experience.