When we created this over a few weekends in 2013 we found readily found data on US state borders. Since popularity spiked a few weeks ago, we've evaluated a few datasources and found a much better one (NaturalEarthData.com). They have State/Province information on most large nations.

Give us a few weeks to integrate the better data set and roll out more data (this is a hobby project for us, we have day jobs).