The upper house of Tennessee's General Assembly is called the Senate. The state is divided into 33 senatorial districts, from each of which one senator is elected. Senators are elected to four-year terms with those from even-numbered districts being elected in the same general election, and those representing odd-numbered districts being elected two years later. Thus, about half of the 33 senators are standing for election at the same time. Re-election to the Senate is constitutionally permissible, as it is in the House, and there is no limit on the number of terms a legislator may serve.To qualify for election to the Senate, one must be 30 years old, a U.S. citizen, a state resident for three years and a resident of the district in which he is elected for one year immediately preceding his election.