Questions about the characteristics of Members of Congress, including their age, education, previous occupations, and other descriptors, are of ongoing interest to Members, congressional staff, and constituents. Some of these questions may be asked in the context of representation, in efforts to evaluate the extent to which Members of Congress reflect their constituencies and the nation at large. In other instances, questions arise as to how the characteristics of Members have changed over time, which may speak in part to the history of Congress. A challenge of discussing Member characteristics in a manner that allows comparison across the history of Congress is the identification of characteristics and reliable data on those characteristics that are collected in a consistent manner over time. No government entity has collected data on Members in a consistent manner for all Congresses. Congressional sources, including entries in the online Biographical Directory of the United States Congress , or the print versions of the biennial Official Congressional Directory , are compiled by the House and Senate, based on information reported by Members. Some academic and journalistic sources provide data on a limited number of Member characteristics over a variety of time periods. While these sources provide some information, they do not report various descriptive characteristics for all Members or all Congresses in a consistent manner. Biographies created by Members for official or campaign purposes are another potential source; those are not readily retrievable for all Members in the Congresses for which this report provides data, and do not report various characteristics for all Members in a uniform manner. This report provides profiles of Senators and Representatives based on selected characteristics since 1945. Data are drawn from the CQ Press Electronic Library, CQ Congress Collection (hereafter CQ Press), a subscription database that provides data on Members and a range of characteristics. Data provided in this report are based on the number of Representatives and Senators who took seats on the first day of a new Congress. The CQ Press database does not contain information on Members who have served as Delegates or Resident Commissioner for Puerto Rico. Table 1 provides the number of Members who took seats on the first day of the 79 th – 113 th Congresses and the years those Congresses met. The report provides data on the following characteristics: age, including the oldest and youngest Members of the House and Senate; sex; previous occupation; race and ethnicity; education; religion; and military service. For each characteristic category, a summary is provided. In some categories, the report provides data on the U.S. population that may be comparable to data available on Members of Congress, as discussed in more detail below. Following the characteristic summaries, the report provides a number of tables that provide the detailed data by the category on which the summaries are based. All data tables appear in the " Member Characteristics Data Tables " section. A detailed discussion of the methods used to develop the data presented in the report, and efforts to provide comparison between Member characteristics and the American public, is provided in an Appendix . Due to differences in data collection or characterization, data in other studies on Member characteristics may differ from those presented in this report. In general, the ages of Members of Congress and the U.S. population have increased slowly since 1945. Figure 1 provides the median ages of Representatives and Senators in Congresses since 1945, and the U.S. population from the 1940-2010 decennial censuses. Data tables with the mean, or average, and median ages of Members and lists of the oldest and youngest Representatives and Senators, in Congresses since 1945 are provided in the " Age " section, below. In the House, between the 79 th and 98 th Congresses, the ages of Members fluctuated narrowly. The lowest median age in the House, 48.4 years, was recorded in the 98 th Congress. Thereafter, the median age of Representatives began gradually increasing. The 113 th Congress held record highs for the House with median ages of 57.5 years for Representatives. The median age of Senators fluctuated narrowly between the 79 th and 97 th Congresses when it reached a low of 51.7 years. The 110 th Congress held a record high for the Senate with a median age of 62.8 years. In the 113 th Congress, the median age of Senators was 61.7 years, a slight change over the previous two Congresses. The median age of the U.S. population in the 2010 census was 37.2 years. The significant age difference between the U.S. population and Representatives and Senators is explained in part by the scope of people counted in the United States. Census data provide information for all U.S. residents of any age from birth until death. To hold office in the House, the Constitution specifies that a Member must be at least 25 years old. A Senator must be at least 30 years of age. Median ages of Members of Congress are higher than in the U.S. population, since the congressional statistics are calculated on the basis of small numbers of adults in an age-restricted group. Until the early 20 th Century, no women served in Congress. Nine decades later, the 113 th Congress has the highest number of female Representatives and Senators ever to serve, but at levels far below that of the general population. Figure 2 provides the distribution of female Members of Congress for Congresses since 1945, the distribution of men and women in each chamber in the 113 th Congress, and the U.S. population, based on the 2010 census. Data on the percentage of female and male Representatives and Senators in Congresses since 1945 are provided in the " Sex " section, below. The first female to serve in the House, Jeanette Rankin of Montana, was elected to the 65 th Congress (1917-1919). Although no women were elected to the 66 th Congress (1919-1921), during which Congress proposed and the states ratified the 19 th Amendment to the Constitution granting women the right to vote, women have served in the House in every Congress since. In the Senate, the first female to serve was Rebecca Latimer Felton of Georgia, who was appointed to the Senate on October 3, 1922, following the death of Thomas E. Watson. Aged 87, she served for only 24 hours while the Senate was in session. The next female in the Senate, Hattie Caraway of Arkansas, was appointed on November 13, 1931, to fill the vacancy caused by the death of her husband, Thaddeus H. Caraway. She became the first woman elected to the Senate on January 12, 1932, when she won special election for the remainder of the term and was reelected to two additional terms, serving in the Senate for a total of 14 years. With only a few exceptions, at least one female Senator has served in each Congress since then. According to the 2010 census, the total population is 50.7% female and 49.3% male. According to the Census Bureau, there have been more females than males in the United States since the 1950 census. The percentage of female Representatives has fluctuated since the 79 th Congress. The House was more than 95% male until the 99 th Congress. The percentage of women doubled, to 10.8%, in the 103 rd Congress, before reaching nearly 15% at the beginning of the 109 th Congress. With a few exceptions—most recently from the 111 th Congress to the 112 th Congress—the percentage of Representatives who are female on the first day of a Congress has generally increased from one Congress to the next. Women did not hold 2% of the seats in the Senate until the 87 th Congress, and did not surpass this until the beginning of the 103 rd Congress, when their percentage tripled to 6.0%. The number of female Senators has remained steady or grown ever since, and membership in the 113 th Congress is 20% female. Representatives and Senators bring an array of work experiences with them to Congress. Figure 3 provides a summary of previous occupations of Representatives and Senators in the 113 th Congress. Since 1945, careers in law and public service are common, but Members have also served as astronauts, entertainers, teachers, and practiced numerous trades. Representatives and Senators have generally similar occupational backgrounds. Most of the occupation data are categorized in the CQ Press data into one of 20 broad subcategories, including, among others: acting/entertainer; business or banking; journalism; law; public service/politics; and real estate. These and other categories provide a relatively simple way to summarize professional experiences for thousands of diverse Members who have served in Congresses since 1945. It is important to note that the CQ Press data provide an overview of pre-congressional careers, but leave some questions unanswered. The CQ Press data provide up to five occupational categories for each Representative and Senator. This report provides data on the first—and in some cases, only—occupation provided by CQ Press. In the absence of additional information, however, it is unclear how or why these positions were listed, or why they were listed first when more than one occupation was provided. Finally, in some instances, the CQ Press data provide no information on occupation for some Members. In addition, the CQ Press data do not provide detail about what facet of a profession a Member pursued, for how long, or whether he or she did so full-time or part-time. In some cases, CQ Press data identify a specific profession, such as Army officer or professor. These listings provide more detail than the broad categories noted above, but might also overlap with some other categories. As discussed above, a former congressional aide might also categorize his or her work as public service/politics. Due to the organization by CQ Press of Members' previously held elective office in a separate category outside the database, the extent of public service backgrounds as the previous occupation of Members may be significantly understated.