As I point out in my article in the current issue, the combination of three forces:
- The original Constitutional compromise giving two Senate seats to every state, large or small;
- The post-Constitutional patterns of population growth, which leave California with nearly 37 million people and Wyoming with just over half a million; and
- The very recent practice of subjecting almost every Senate action to the threat of filibuster, which requires 60 votes to surmount...
.. means that in theory Senators representing only 12% of the U.S. population could block efforts that Senators representing the other 88% support.
In reality, the pattern is not that extreme. The Republican minority in the Senate includes some from highly-populated states -- two from Texas, one each from Florida and Ohio. The Democratic majority includes some from low-population states -- both from Delaware and West Virginia, one each from Alaska and Nebraska.
So in reality, what's the population balance? Counting the new Republican Senator Scott Brown from Massachusetts, the 41 Republicans in the Senate come from states representing just over 36.5 percent of the total US population. The 59 others (Democratic plus 2 Independent) represent just under 63.5 percent. (Taking 2009 state populations from here. If you count up the totals and split a state's population when it has a spit delegation, you end up with about 112.3 million Republican, 194.7 million Democratic + Indep. Before Brown's election, it was about 198 million Democratic + Ind, 109 million Republican.)