I've taken my polling from the Wikipedia page Opinion polling for the Democratic Party (United States) Presidential Primary, 2008 webpage. I'm not much of a poll geek, so please do check my sources and point out if I'm missing more recent polls or if Wikipedia is inaccurate.

There is no polling from 16 states and from the District of Columbia. Three of the states (Maryland, Minnesota and Hawaii) are fairly safe blue. The rest of them range from safe red to absolutely unwinnable for a blue candidate and are mostly concentrated in the interior northwest. The states tend to be fairly unimportant in terms of the mechanics of the race for at least two out of three reasons: conservative leanings, small size, late primaries.

We do have polling from every state putting forward a serious candidate (if you like Gravel, pretend I'm including him because he now lives in Virginia.) The results are interesting.

Nationally, Chris' most recent summary has Clinton at a little under 35% with Obama about 12 points behind and Edwards a further 10 points back. Similarly, she's ahead in almost every state thus far polled. The exceptions are Iowa (going by poll averaging), South Carolina (in the two most recent polls I've seen, although not in poll averages as yet), Oklahoma (where a poll that's nearly two months old has her tied with Edwards), Illinois, North Carolina and New Mexico. Three guesses what that last trio have in common.

Yes, Obama, Edwards and Richardson appear to lead in their home states. The monthly polling of NC by Public Policy Polling (D) since March has consistently shown Edwards ahead. The margin, however, has varied. The April poll gave him a 14 point lead over Clinton, but in general polling has shown a much closer race. Aside from that poll Edwards hasn't got above 33%, whilst Clinton's been running between 21% and 27% and Obama's been as high as 25% and as low as 19%.

The only polling for Illinois is from January. Obama and Clinton are the only two to rise above 5%. That said, there just isn't enough data here to form an impression of the race. Obama's approval rating is high enough that it seems eminently plausible that he's leading in the state, but we can't say anything more than that.

The picture's not much better in New Mexico. There are two polls, but one of those is from January and the other from April. Richardson leads in both from Clinton, in the latter case by 10 points. However, he's still only drawing around a third of the voters, so the main effect is to make the race for second closer.

In Delaware the only poll dates from the start of March. Clinton leads on 34%, with Biden in second with 21% and Obama within the margin of error. In Connecticut home state advantage would appear to be even less powerful. The most recent Quinnipac poll shows Dodd in 5th place with only 6%, although it's worth noting that Gore is included and the only CT poll without him has Dodd with 14%. In Ohio Kucinich's most recent poll showing (again including Gore) was 2%.

Clinton's most recent polling from New York shows her hovering around the 40% mark. Her advantage is around 30 points. This is in a poll which includes Gore, but even if one totals up the showings of Gore, Obama and Edwards they'd still only come to around 33%, and if one looks at the trends it appears Gore voters would probably vote for Clinton if he wasn't included. In Arkansas, her other home state, a March ARG poll had her at 49% without Gore and her advantage was again above 30 points.

So it's a mixed picture. None of the candidates are from an early state and the polling verges from sporadic to nearly non-existent for their home states. And there definitely is a home state advantage for everybody except Kucinich, who isn't likely to do well anywhere and doesn't wield much influence in Ohio politics. Even Dodd's doing a few points better than normal in CT than elsewhere. But nobody's able to get much more than 35% in their home states, except for Clinton, who's able to get that in a lot of places anyway.

Compare that to 1976, when Robert Byrd won West Virginia despite having no real desire to be president evident. Home state advantage isn't worth so much in terms of raw appeal to voters anymore. Certainly it benefits some more than others. Richardson, for example, probably benefits because of his high profile as a governor, whereas Biden is legislating for all of America and it's harder for him to make a significant difference in Delaware that makes him seem presidential. There's also the influence of local party support to factor in, since Edwards, for example, has been endorsed by the entire NC Democratic congressional delegation.

Yet the current state of the primaries, wherein Clinton appears to lead by around as much in Utah as in Maine certainly shows that a regional campaign is becoming less viable as a tactic - especially since the south has lost its Dixiecrats - and represents a decline in the power of favourite son candidacies in primaries and possibly also in general elections. In no case does a candidate appear to be gaining more than about 25% on their national performance, and even that is rare. Following current trends, in a few decades the advantage will be almost negligible.

Now, providing references to your sources, prove me wrong.