Roman Catholic Church law requires cardinals, the pope's chief advisers, to elect his successor. There are 208 cardinals from 68 nations but only those under age 80 are eligible to vote.
Of the 119 electors as of January 2013, most (67) were named by Benedict XVI and the rest (52) by Pope John Paul II.
Although the USA has only 6% of the 1.2 billion global Catholic population, it has 19 cardinals including 11 electors, about 10% of the total electors.
Electors by region:
North America, 18
South America, 13
Central America, 3
Countries with the most cardinal-electors:
United States: 11
Brazil, India, Spain: 5 each
France, Mexico, Poland: 4 each
U.S. electors (year named)
Raymond Burke, (2010) archbishop emeritus of St. Louis, now head of the Vatican's high court, the Apostolic Signatura
Daniel DiNardo, (2007) archbishop of Galveston-Houston
Timothy Dolan, (2012) archbishop of New York, president of the U.S. Conference of Catholic Bishops
Francis George, (1998) archbishop of Chicago
James Harvey, (2012) of Milwaukee, former head of the papal household and now archpriest of a major basilica in Rome
William Levada, (2006) archbishop emeritus of San Francisco, retired after heading the Congregation for the Doctrine of the Faith
Roger Mahony, (1991) archbishop. emeritus of Los Angeles
Edwin O'Brien, (2012) archbishop of Baltimore
Sean O'Malley, (2006) archbishop of Boston
Justin Rigali, (2003) archbishop emeritus of Philadelphia
Donald Wuerl, (2010) archbishop of Washington, D.C.
U.S. cardinals too old to vote:
William Baum, Major Penitentiary emeritus
Edward Egan, Abp. emeritus of New York
William Keeler, Abp. emeritus of Baltimore
Bernard Law, Abp. emeritus of Boston
Theodore McCarrick, Abp. emeritus of Washington
Adam Maida, Abp. emeritus of Detroit
James Stafford, Major Penitentiary of the Apostolic Penitentiary
Edmund Szoka, governor emeritus of the Vatican City State
SOURCE:The Catholic Almanac