Scion is a line of models produced by Toyota Motor Corporation. Toyota cars were originally only sold in Japan, but since its creation in 1937, the company has grown into a huge corporation with factories in many other countries worldwide. Although there are Toyota factories all over the world, the Scion line of models was only intended for sale in North America, so it is only manufactured there. The following are brief descriptions of biggest countries of North America with respect to Toyota Scion production and availability.
The original Scion models, the Scion xB, the Scion xA and the Scion tC, were only intended for sale in the United States, so they were only manufactured in the United States. All subsequent Scion models are also currently being mass produced in the United States. This is good news if you live in the US and want a Scion, because supply is higher around manufacturing plants, which drives down price, and shipping costs are also kept to a minimum. This means that residents of the United States will get the cheapest deals on new Scion models.
While there are no Scion models being built anywhere in Canada as of 2009, the newest generation of 2010 Scion models are expected to be manufactured in Toronto. Even if you don't want to wait until 2010, you can still get any Scion model relatively easily by having it shipped from the United States.
There are currently no plans to start manufacturing Toyota Scion models in Mexico, but they can still be shipped with minimal cost from the United States.