Just because I love beating a dead horse on how stupid the Senate is, I thought I'd look through the last few cycles to see which state was responsible for our needing Arlen Specter's cowardice to break a filibuster. The answer is South Dakota in 2004, electing John Thune over Tom Daschle by a margin of 4,508 votes. I doubt that any of those 4,508 South Dakotans had any inclination that their votes would be responsible for allowing Senate Republicans to obstruct the agenda of an extremely popular new Democratic president and his massive congressional majorities five years later. It's impossible to blame them or the voters of Alaska (2004), Florida (2004), Tennessee (2006), or Georgia (2008) for 59 rather than 60 Democratic Senators.
But when you combine six year terms, huge population disparities across states, staggered elections, small chamber size, and an arbitrary 60-vote requirement on major legislation, you get South Dakotans in 2004 deciding the fates of stimulus, healthcare, EFCA, judges, and more in 2009 and 2010.