Public Transit... to Another Country?

A little trivia for everyone tonight.

Not counting a few Amtrak routes (Adirondack to Montreal, Cascades to Vancouver, and Maple Leaf to Toronto), are there any public transit routes between the United States and another country?

Ok, so if you know anything about current events, the border between Mexico and the United States is a hot topic. So I think a United States transit agency would be very reluctant to run service to Mexico even with customs control. San Diego comes very close to the border on their trolley service but does not cross it. El Paso Sun Transit does not go across the Rio Grande, and neither does Laredo El Metro.

But what about our neighbor to the north, eh? Yes, I found the Tunnel Bus. This service, run by Transit Windsor, connects Detroit with Windsor, Ontario through the submerged Detroit-Windsor Tunnel. Service is offered 7 days a week and costs $3.75. I was about to ask whether that was Canadian or American dollars, but I guess it doesn't matter much right now. Just remember the holiday schedule is based on Canadian holidays.