Detroit-Windsor Tunnel — Passenger Vehicles Only

Legal Disclaimer: This information reflects Detroit cannabis law as of July 2026 and is for educational purposes only. It is not legal advice. Laws and regulations change — always verify current rules with the Michigan Cannabis Regulatory Agency or a qualified attorney. Cannabis remains illegal under federal law.

Last verified: April 2026

The Crossing

The Detroit-Windsor Tunnel is a vehicular tunnel beneath the Detroit River connecting downtown Detroit and downtown Windsor. Opened in November 1930, it is one of only a handful of vehicular tunnels connecting two countries. The tunnel handles passenger vehicles only; commercial trucks are not permitted (a structural and safety constraint, not a regulatory one).

Tolls

The Detroit-Windsor Tunnel passenger toll is US$9 one-way — less than the Ambassador Bridge’s US$10 but more than the planned Gordie Howe International Bridge’s US$5.75. The tunnel is jointly owned by the cities of Detroit and Windsor; it is publicly operated rather than privately held, distinguishing it from the Ambassador Bridge.

Why No Trucks

The tunnel’s clearance, ventilation, and grade limitations make it unsuitable for commercial truck traffic. All cross-border commercial trucks must use the Ambassador Bridge or the Blue Water Bridge in Sarnia. The result: tunnel users are predominantly passenger-vehicle commuters and tourists.

Approach Routes

The U.S. approach is via Jefferson Avenue and downtown Detroit (the Renaissance Center area). The Canadian approach is via the Goyeau Street area of Windsor. Both approaches sit in dense urban downtown areas, distinguishing the tunnel from the Ambassador Bridge’s more highway-style approach corridors.

Cannabis at the Tunnel

The Detroit-Windsor Tunnel Port of Entry is federal jurisdiction operated by U.S. Customs and Border Protection (CBP) on the U.S. side and the Canada Border Services Agency (CBSA) on the Canadian side. Cannabis at the Port of Entry is a federal violation under the U.S. Controlled Substances Act and the Canadian Customs Act, regardless of cannabis legality in Michigan or Ontario.

Practical guidance for tunnel users:

Do not carry cannabis or cannabis-derived products of any kind — including CBD with any THC content
CBP officers can search vehicles at their discretion at the U.S. Port of Entry
CBSA officers can search vehicles at their discretion at the Canadian Port of Entry
Drug-detection dogs may be present at either Port of Entry
Cannabis residue or paraphernalia can trigger questions and additional screening
Admissions of past cannabis use can result in lifetime inadmissibility for non-U.S. citizens (INA § 212(a)(2)(A)(i)(II))

Tunnel-Specific Risks

The tunnel’s confined-space environment creates some specific cannabis-related risks beyond the general border-crossing risks:

Cannabis odor in a vehicle is more readily detected in the enclosed tunnel environment than on an open bridge
Air quality monitoring in the tunnel includes some compounds; cannabis combustion products can be detected
The compact tunnel-toll-and-screening area on both sides means a single secondary-screening referral can disrupt traffic flow noticeably

The Casino-Tourism Use Case

The tunnel is the primary crossing for casino tourism between Detroit (MGM Grand, MotorCity, Hollywood Casino at Greektown) and Windsor (Caesars Windsor). Both sides operate strict no-cannabis-on-property regimes; crossing the tunnel for casino tourism is common, crossing with cannabis is not advisable in either direction.

Day-Trip Tourism

The tunnel sees significant day-trip tourism in both directions:

U.S. residents visit Windsor for its Riverside cycling paths, Walkerville Brewery District, casino, and the broader Windsor restaurant and entertainment scene
Canadian residents visit Detroit for Tigers / Lions / Pistons / Red Wings games, the Detroit Institute of Arts, the Eastern Market, the Riverwalk, and downtown entertainment

Cross-border day-trippers should plan zero cannabis transport in either direction; consume before crossing or after returning.

The Windsor Cannabis Market — A U.S.-Resident Perspective

Ontario operates a regulated retail cannabis market under the Cannabis Act and the Ontario Cannabis Store (OCS) framework. Windsor has multiple licensed cannabis retailers within short walking distance of the Detroit-Windsor Tunnel exit. U.S. residents who consume cannabis legally in Windsor under Ontario law cannot bring product back across the tunnel; once you cross back into the U.S., the product is contraband under federal law. The legal consume-in-Windsor / illegal-bring-back asymmetry is a structural feature of cross-border cannabis tourism.

Lifetime Inadmissibility for Non-Citizens

For non-U.S. citizens crossing into the U.S. via the Detroit-Windsor Tunnel, an admission of past cannabis use to a CBP officer can result in lifetime inadmissibility. CBP discretion governs; lying is a separate federal offense. See Lifetime Inadmissibility.