The purpose of this study was to find out what effect tariff rates had on the territorial growth of late 19th century European, American, and Japanese empires. Many, if not most, historical studies of late 19th to early 20th century imperialism have explained it as a cultural phenomenon. Others have hypothesized that the territorial growth owes some explanation to protectionism. This study found that, given a three year lag, tariff rates can explain a little more than 50% of the aggregate territorial growth rate with diminished results when observing country-by-country.