Two fewer U.S. Senators are dying in office per year on average over the past half-century than during the previous 60 years
Two long-serving members of Congress died in 2013 - Democratic U.S. Senator Frank Lautenberg of New Jersey and Republican U.S. Representative Bill Young of Florida.
Aging U.S. Representatives are given more natural opportunities to retire - coming up for reelection every two years - compared to U.S. Senators who serve in six-year stretches.
That may be why the nation's upper legislative chamber has lost four long-serving members over the last five years (all Democrats): Lautenberg in June 2013, Daniel Inouye of Hawaii in December 2012, Robert Byrd of West Virginia in June 2010, and Ted Kennedy of Massachusetts in August 2009.
Despite these high profile deaths in the chamber, overall much fewer U.S. Senators are dying in office compared to previous decades.
The institution has not lost more than one sitting U.S. Senator in a calendar year in 35 years, when Democrats Lee Metcalf of Montana, Herbert Humphrey of Minnesota, and James Allen of Alabama died in 1978.
The 1990s also saw the longest gap between deaths of sitting Senators in U.S. history at 7 years, 1 month, and 16 days between the death of Democrat Quentin Burdick of North Dakota in September 1992 and Rhode Island Republican John Chafee in October 1999.
There have been only seven periods in which no U.S. Senators have died in office for three consecutive years, and four of these stretches have occurred since the 1970s: 1973-1975, 1979-1982, 1993-1998, and 2003-2006.
The only other such streaks occurred between 1794-1797 (when the chamber had just 30 to 32 members), 1810-1813 (when it had 34 to 36 members), and 1887-1889 (when it had 76 to 88 members).
More than half of sitting U.S. Senators in history to die in office did so during a 59-year stretch from 1904 to 1962.
A total of 151 members died during this period, or 2.6 per year, of the 300 who passed away in office since the 1st Congress in 1789.
During the 51 years since, from 1963 to 2013, only 30 Senators died in office, or just 0.6 per year.
The largest number of senators to die in one year was seven - in 1918.
That year saw the deaths of Republican James Brady of Idaho (on January 13th), Democrat William Hughes of New Jersey (January 30th), Democrat Robert Broussard of Louisiana (April 12th), Democrat William Stone of Missouri (April 14th), Democrat Benjamin Tillman of South Carolina (July 3rd), Republican Jacob Gallinger of New Hampshire (August 17th), and Democrat Ollie James of Kentucky (August 28th).
Six senators died in 1954, with five each in 1908, 1925, 1936, 1941, and 1945.
June and December have been the most common months for such tragedies - tallying 32 U.S. Senatorial deaths in each, or 21.4 percent of all deaths in the institution's history.
Senators in the 113th Congress survived what has traditionally been the worst stretch for deaths of its members in the last quarter of the year.
Thirty percent of such deaths have occurred in October (27), November (31), and December (32).
That number drops to just 21 percent in January (23), February (14), and March (28).
Deaths on notable dates include:
· Federalist James Burrill of Rhode Island: died on Christmas Day in 1820.
· Democrat Robert Kerr of Oklahoma: died on New Year's Day in 1963.
· Republican Hiram Johnson of California: died on August 6, 1945 - the day the U.S. dropped the atom bomb on Hiroshima.
The most frequent days of the year in which sitting U.S. Senators have died are June 4th, October 14th, November 1st, and December 20th - all seeing four pass away on that day.
The first sitting Senator to die in office was William Grayson of Virginia, one of the original 26 to serve in the 1st Congress.
Grayson served only a year and eight days in office before his death in March 1790.
Arizona and Utah are the only states in which no sitting U.S. Senators have died.
New York has the third lowest such rate, with just two of 59 Senators in history to die in office, or 3.4 percent.
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