Of course there is a strong correlation. The people of the nation and the people of the states are the same people. But the correlation is not absolute, and exists only in so much as the state averages drive the national averages. Some states are more partisan than others.
Massachusetts was certainly a Republican state in 1984. It was also certainly less Republican than the nation, if that's what you want to say.
Philip is correct. The national numbers do not change the state numbers, the state numbers change the national numbers. If California moves to teh Republicans by enough to shift the national numbers by 1% that does not mean a single person in any other state will change their mind and vote differently. No one in Rhode Island is going to say "Well, the national numbers moved toward Bush so it is my responsibility to change my vote so my state moves along with them."
As much as some people would like to put Nader's votes onto Kerry and Gore and Buchanan's and Peroutka's votes onto Bush you can't. Those votes were not cast for those candidates or parties, they were cast for a third party for a reason. If the third party had not run things would be different, but they did run so things are not different.
Let's look at a few states:
BATTLEGROUND STATES:Oregon:
Difference in 2000: .4% D
Difference in 2004: 4.2% D
Change: 3.8% to D
New Hampshire:
Difference in 2000: 1.2% R
Difference in 2004: 1.4% D
Change: 2.6% to D
Ohio:
Difference in 2000: 3.5% R
Difference in 2004: 2.1% R
Change: 1.4% to D
Navada:
Difference in 2000: 3.6% R
Difference in 2004: 2.6% R
Change: 1% to D
Minnesota:
Difference in 2000: 2.4% D
Difference in 2004: 3.4% D
Change: 1% to D
Wisconsin:
Difference in 2000: .2% D
Difference in 2004: .4% D
Change: .2% to D
New Mexico:
Difference in 2000: .06% D
Difference in 2004: .8% R
Change: .86% to R
Iowa:
Difference in 2000: .3% D
Difference in 2004: .7% R
Change: 1% to R
Michigan:
Difference in 2000: 5.1% D
Difference in 2004: 3.4% D
Change: 1.7% to R
Pennsylvania:
Difference in 2000: 4.2% D
Difference in 2004: 2.5% D
Change: 1.7% to R
Missouri:
Difference in 2000: 3.4% R
Difference in 2004: 7.2% R
Change: 3.8% to R
Florida:
Difference in 2000: .01% R (maybe)
Difference in 2004: 5% R
Change: 5% to R
What do we see here? Very little movement. Five states voted mroe Democrat than last time and 6 mroe Republican. Most states saw very little change. Kerry may have been helped in New Hampshire by being from a neighboring state. To see if this is real movement we need to wait another cycle or two.
Same goes in FLorida. Was the 5% gain real movement or was it bumped by the hurricane relief efforts Bush gave?
The only state I think saw genuine movement that will likely last is Missouri. It seems to be joining the "solid south" for the Republicans. Minnesota, Oregon and Michigan may have also seen some real movement. Everything else is too little or the state has too long a history of being a battleground for the movement to mean much.
SECOND TIER BATTLEGROUND STATESWashington:
Difference in 2000: 5.6% D
Difference in 2004: 7.2% D
Change: 1.6% D
Virginia:
Difference in 2000: 8% R
Difference in 2004: 8.2% R
Change: .2% to R
Arizona:
Difference in 2000: 6.3% R
Difference in 2004: 10.5% R
Change: 4.2% to R
Louisiana:
Difference in 2000: 7.7% R
Difference in 2004: 14.5% R
Change: 6.8% R
Tennessee:
Difference in 2000: 3.9% R
Difference in 2004: 14.3% R
Change: 10.4% to R
These states were all thought at one point to be in play to one degree or another and each was thought to be removed from teh table by the end of the campaign.
The only state that moved in the Democrats favor is Washington, everything else moved Republican to one degree or another. Virginia hardly moved at all.
The big jump in Tennessee and Louisiana could be, in part, due to the lack of a southerner at the top of the Democratic ticket. Either way they mvoed Republican solidly enough to impact the national number.
NON-BATTLEGROUND STATESVermont:
Difference in 2000: 9.9% D
Difference in 2004: 20.1% D
Change: 10.2% to D
North Carolina:
Difference in 2000: 12.8% R
Difference in 2004: 12.5% R
Change: .3% to D
California:
Difference in 2000: 11.8% D
Difference in 2004: 10% D
Change: 1.8% to R
Georgia:
Difference in 2000: 11.7% R
Difference in 2004: 16.6% R
Change: 4.9% to R
Utah:
Difference in 2000: 40.5% R
Difference in 2004: 45.5% R
Change: 5% to R
Rhode Island:
Difference in 2000: 29% D
Difference in 2004: 20.8% D
Change: 8.2% to R
Vermont saw a real, solid mvoe to the Democrats. North Carolina saw a slight move that could possibly be frm having the VP on the Democrats be from this state. We'll have to wait 4 years and see.
THe big surprise here is Rhode Island running to Bush. I did not see that happening.
So where did the movement occur? Where did Bush gain his popular vote victory? Mostly in mid sized Republican strongholds turning out for him, especially in the south. In many of these states his margin of victory doubled or more having a noticable impact on the national vote percentages. None of Kerry's big movers were large enough to have that effect.
I think the main cause for the change in the national numbers is the lack of a southerner at teh top of the D ticket and the Kerry campaign's "small state" strategy.