Qualifications, Perquisites, and Membership The Constitution provides that a senator must be 30 years of age, have been a citizen of the United States for nine years, and be a resident of the state from which he or she is elected. Benefits include health and life insurance, a contributory retirement plan, and a tax-deferred savings plan. Senators receive an annual allowance for maintaining staffs in Washington, D.C., and in their home states, the sum being determined by the population of the state. Funds are provided for senators to rent office space in and travel to and from their home states, and for office supplies and expenses. Senators have the franking privilege use of the mails without charge for official business, with limits set according to state population.
Senators also enjoy immunity from some kinds of arrest and legal action.
The average senator is a white male lawyer and a veteran of the armed services. Most senators who are not lawyers are businesspeople. The average senator, unlike the average member of the House of Representatives, can usually count on gaining statewide visibility and perhaps regional or national notice as well if he chooses to speak on important issues of the day. Elections Until 1913, state legislatures elected senators. Thus the party affiliation of the senator was dependent on which party controlled the state legislature, which in turn was dependent on state elections.