NBPTS develops the professional standards nationally. Also prominently located on this site's first page is a link to each state certification agency.
The Praxis Series Assessments provide tests and other services that states use as part of their teaching licensing certification process.
Links to most states' teacher certification sites.
From U.S. Department of Education
Teacher Certification Requirements for 50 states - compiled by U of Kentucky College of Education
Apply for Your First Minnesota License or Renew Your License Online
Information on the certification process for the state of North Dakota.
Praxis, CSET, CBEST, and RICA test preparation