The large shifting of seats in the US House of Representatives from red to blue may need little more explanation than this: in arguably the worst economic conditions since the Great Depression, the country voted arguably the largest backlash against the party in power since the Great Depression.

I suspect that, once you get beyond the partisans and ideologues, the folks we call "swing voters" took a pretty intuitive and reasonable view of things: they don't blame Obama and the Democrats for causing the recession, and they suspect that actions taken by Obama and the Democrats have kept things from being much worse, but things aren't good, which probably means that Obama and the Democrats don't have the answers to make things good.

Just a little something to keep in mind as you watch returns tonight. There's a reason that Massachusetts's congressional seats are going to remain all, or mostly, in Democratic hands despite whatever number of seats flip from blue to red across the country.

The seats that are likely to flip are not random. They are almost all, in order of vulnerability: 1) open seats; 2) first-term incumbents; 3) districts where McCain beat Obama (many of which have grown increasingly conservative over the incumbent's tenure); or 4) two-term incumbents, who have only won in the '06 and '08 Democratic wave elections.

Interesting fact: overall turnout numbers were almost exactly the same in the November 2006 statewide election (Deval Patrick) and the January 2010 special US Senate election (Scott Brown). In 2006, 2,243,835 people cast ballots in Massachusetts; in 2010, it was 2,249,026. Turnout percentage was lower, because far more people are registered to vote now, thanks in large part to the huge 2008 registration effort.

Through 9:00am, 28,180 people had voted in Boston, according to official numbers obtained by the Phoenix. That's a very strong 7.6% of registered voters, and roughly 5500 more than had voted by 9:00 in the January special US Senate election between Scott Brown and Martha Coakley.

Of particular interest, turnout appears to be relatively strong in many minority precincts.

The GOP needs to gain 39 net seats in the US House of Representatives to take majority control. That's in addition to the 20 open Republican seats that need to be filled; but Democrats are likely to win two of those, plus knock off two Republcan incumbents; and plus you have to factor in a GOP incumbent beaten in the primary...

In my handy-dandy couch-potato's guide to the election, in the current issue of the Boston Phoenix, I gave you 20 key US House races to watch over the course of the evening.

I'm now going to give you 40 more -- 20 "must-wins" for the Democrats, and 20 "must-wins" for the Republicans.

The first batch are races that Democrats have expected to win; if any of these go to the GOP -- or even if they remain too close to call long after polls close -- that would indicate a very big night for Republican gains in the House.

Here's an intriguing thing to watch election night: when the dust settles and everyone's sworn in, will more Americans be living under Democratic or Republican Governors?

Most recent popuilation estimates say there are roughly 306 million Americans living in the 50 states (not including DC, which has no governor, and the territories, which I'm not including).