Length of terms of state senators. The length of terms in state senates in the 50 American state senates is either two years or four years. Senators in 31 states have a four-year term. Senators in 12 states have a two-year term. Senators in seven states (Arkansas, Delaware, Florida, Illinois, Minnesota, New Jersey and Texas) have terms that are sometimes two years and sometimes four years, depending on the proximity of the election to the legislative re-apportionments that occur every 10 years after a federal census.