While you can physically walk across the border between the United States and Canada at designated legal ports of entry, you cannot simply "walk across" at any random point along the 5,525-mile boundary. Crossing at a non-designated area is illegal and can lead to arrest, deportation, or permanent bans from entering the country. At official land crossings, such as the Rainbow Bridge at Niagara Falls or the Peace Arch in Washington, there are dedicated pedestrian lanes where you must present valid travel documents—typically a passport, an NEXUS card, or an Enhanced Driver's License—to a border services officer. You will be questioned about your purpose for visiting, the duration of your stay, and whether you are carrying any prohibited goods or large amounts of currency. The process is very similar to crossing in a vehicle, requiring a formal inspection and declaration. It is a common misconception that the border is "open" in rural or forested areas; both countries employ sophisticated surveillance technology, including ground sensors, cameras, and aerial patrols, to monitor unauthorized crossings. Therefore, while "walking" is a valid mode of transport at a legal checkpoint, the legal requirements for entry remain as strict as they are for air or vehicle travel.