Subnational comparison gained prominence first in American politics. Now, comparative politics increasingly employs this method across national boundaries. This shift is known as transnational comparison.

This approach builds on subnational study while addressing its inherent challenges. It leverages both cross-country differences and within-country variations effectively.

Researchers have developed a typology to guide studies of subnational regimes. By outlining distinct comparative strategies, this work helps scholars navigate different research stages and answer varied substantive questions.

These methods advance political science beyond traditional nation-centered approaches.