Thanks to the reader who suggested the correction and clarification I’ve added below.

The U.S. Census Bureau confirmed this week that Iowa will lose a Congressional district following the 2010 census unless we experience unprecedented (for Iowa) population growth in the next two years:

During the past eight years, Iowa has gained as many people – about 76,000 – as states like South Carolina and Virginia gained between 2007 and 2008 alone.

To retain the congressional seat, the state would have to gain nearly twice that number by 2010, according to projections by Election Data Services, a Washington, D.C.-based consulting firm that analyzes the impact of demographics on politics.

Don’t get your hopes up: we are going down to four Congressional districts. No one knows what the new map will look like, but it’s likely that the 2012 race in the new third district will determine whether Iowa Democrats (who now hold a 3-2 edge in U.S. House seats) gain a 3-1 advantage or have to settle for a 2-2 split.

Note: A non-partisan commission draws up the new Congressional map after each census in Iowa, so Democratic gerrymanders will not take place, even if Governor Chet Culver wins re-election in 2010 and Democrats hold their majorities in the state House and Senate. (Clarification: if the Democrats maintain control of the legislature, they have the option of rejecting the first and/or second map produced by the non-partisan commission. Republicans rejected the first map proposed after the last census.)

Most of what’s now the fifth district, represented by Republican incumbent Steve “10 Worst” King, is likely to become the new fourth district. It makes no difference whether the new counties added to IA-04 come from the current third or fourth districts–that is going to be a safe Republican seat.

Given the voting trends in eastern Iowa, I assume the new first and second Congressional districts will still be relatively safe for Democrats. (Remember, fewer than 10 Republicans in the whole country represent districts with any kind of Democratic partisan lean.) Either Bruce Braley or Dave Loebsack may need to move if the new map throws Waterloo (Black Hawk County) in the same district as Mount Vernon (Linn County), but that should not present much of a problem.

The big question mark is what happens to IA-03. Polk County will remain the largest county in the district, but it won’t be as dominant in the new district as it is now. Roughly 75 to 80 percent CORRECTION: A majority of the votes in the current third district come from the county containing Des Moines and most of its suburbs.

In which direction will IA-03 expand? If the counties added to it come mostly from the southwest, Republicans will have a better chance of winning the district. One reason Greg Ganske beat longtime incumbent Neal Smith in the 1994 landslide was that Smith’s fourth district had lost Story and Jasper counties, and gained a lot of southwestern Iowa counties, following the 1990 census.

If IA-03 includes more counties from the southeast, Democrats would be better positioned to hold the seat, although it’s worth remembering that Ottumwa resident Mariannette Miller-Meeks carried seven southern counties in her unsuccessful challenge to Loebsack in IA-02 this year.

Speaking at an Iowa Politics forum in Des Moines last month, Miller-Meeks said she was leaving her ophthalmology practice at the end of 2008. She strongly suggested that she will run for office again. Whether that means another bid for Congress or a run for the state legislature was unclear.

Miller-Meeks has little chance of winning a district as strongly Democratic as IA-02, but I could easily see her taking on Leonard Boswell if Wapello County ends up in IA-03 after the next census. The Des Moines Register has endorsed Boswell’s challengers before and would back any credible Republican opponent against him.

The Republicans’ best chance in a third district stretching to the south, though, would be to run someone with strong Polk County connections to keep down the Democratic margins there. I don’t have any idea which Republicans have their eye on this race.

If IA-03 expands to the north, it’s good news and bad news for Democrats. Story County and Marshall County are reasonably strong territory for the party. On the down side, current fourth district incumbent Tom Latham lives in Story County. Latham is a mediocre Republican back-bencher; what else can you say about a seven-term incumbent whose big achievement on health care, according to his own campaign, was co-sponsoring a bill that never made it out of committee?

However, Latham has obviously used his position on the Appropriations Committee to build up a lot of goodwill in the district. He just won re-election by 21 points in a district Barack Obama carried by 8 percent, and he even carried Story County.

I don’t care to run Boswell or a non-incumbent Democrat (in the event of Boswell’s retirement) against Latham in a redrawn IA-03. I’m not saying Democrats couldn’t hold the seat in those circumstances, but I feel it would be a tough hold.

We would be better off electing a new, ambitious Democrat to Iowa’s third district in 2010, so we can run a rising star in the majority party against Latham, if it comes to that. Actually, we’d have been better off if Boswell had retired in 2008, allowing someone new to compete for this seat as a two-term Democratic incumbent in 2012. But what’s done is done.

Anyone think there’s a chance Boswell will reconsider his promise to run for re-election in 2010?

If Democrats still control the state legislature after 2010, should they reject the first new Congressional map suggested by the non-partisan commission if that map puts Story County in IA-03?

What kind of map would give Democrats the best chance of holding the third district?

I look forward to reading your absurdly early speculation about the 2012 races in the comments.

For those who are interested in the national implications of the post-census reapportionment, DavidNYC created a chart showing which states are likely to gain or lose Congressional districts.

Chris Bowers has already created a 2012 electoral college map, and even with one fewer electoral vote, Iowa will remain important to Obama’s re-election chances. You should click over and read the whole post yourself, but the good news is that Obama has a clear path to 270 electoral votes in 2012 even if he loses Ohio, Florida, Virginia, Indiana and North Carolina.

UPDATE: John Deeth looked ahead to the 2012 Iowa races in this post last week. He concluded that in order to win three out of the four Congressional districts, Iowa Democrats will need to 1) beat Latham in 2010, and 2) get Boswell to retire in 2012. Click over to read how he reached that conclusion.