By the numbers: Half of the senators who voted for PPACA will be gone in 2015

29.4 million: That's the combined population of the nine states that Republicans flipped from Democratic control according to 2010 Census 2010 data, a total that's smaller than California's population of 37.3 million. Four of the states—Alaska, South Dakota, Montana and West Virginia—together have fewer residents than 25 of the 50 states. Recall that the Constitution guarantees each state two senators regardless of population. This was essentially a small-state Senate election. In 2015, Republicans will control 30 of the 50 Senate seats in the 25 least-populous states, while Democrats will control 26 of the 50 in the most populous states.

See also: GOP groups target Senate incumbents on health care.

132: The seat Cassidy wrested away from Landrieu had been in Democratic hands for almost 132 consecutive years, dating to the Reconstruction era. The Republican win in Louisiana, a state that Bill Clinton won twice, swept away one of the last remnants of the once-Democratic "Solid South." Republicans will hold all 10 Senate seats and all five governorships in the Deep South states of Louisiana, Mississippi, Alabama, Georgia and South Carolina.

84: That's the number of U.S. senators who belong to the same political party as the 2012 presidential nominee who carried their states in the 2012 presidential election. This is an extraordinarily high number, the biggest in at least 60 years, according to data compiled by Gary Jacobson, a political scientist at the University of California at San Diego. State voters' choices for president and Senate are coming into even greater partisan alignment, as the Louisiana outcome showed: Landrieu lost by 12 in a state that Obama lost by 17 two years ago. It's getting harder for Democrats to win statewide elections where Republicans win presidential elections, and vice versa, as was detailed in this Bloomberg Politics story on the rise of straight-ticket voting.

53: The number of senators in the 114th Congress in January who will have previously served in the House. That's the highest total since at least 1899, according to Eric Ostermeier's Smart Politics. This total includes Cassidy, who's represented the Baton Rouge area in Congress since 2009. Landrieu did not serve in the House. One wonders if the rising trend of House members graduating to the Senate is contributing to more partisan warfare in the latter chamber.

36: The number of states that will have both senators from the same political party. Twenty states will have two Republican senators. The 16 states with two Democratic senators include Vermont, where liberal independent Bernie Sanders caucuses with the Democrats for organizational purposes and also is chairman of a committee in the soon-to-expire Democratic-run Senate. Democrat Pat Leahy is Vermont's other senator.

20: That's how many women will serve in the Senate, the same number as today. The partisan ratio shifts to 14-6 Democratic from 16-4 Democratic, reflecting the losses of Landrieu and Democrat Kay Hagan in North Carolina and the victories of Republicans Shelley Moore Capito in West Virginia and Joni Ernst of Iowa. The Senate convening in 2015 will be the first in history to have six Republican women, according to the Center for American Women and Politics at Rutgers University.