(Caution - boring civics lesson to follow...)
Here's an example of how the voting goes in individual states, and also of the typical CITY vs COUNTRYSIDE divide in this country. It's a random example, in the state of Indiana which at 11AM NY time today was just
called for Obama.
If you click on this link, http://elections.nytimes.com/2008/results/president/map.html
, and then
click on the state of Indiana (it's a blue state (the Democrat color) along the top of the country, about 1/3 over from the far right, abbreviation "Ind." for those who aren't as familiar with the map), you'll see that Obama only won 15 out of what looks like 150 or 200 counties. The rest of the counties are red, red, and red (Red is the Republican color)! But, these blue counties are the ones with the large population centers (cities), and since states are winner takes all, all of Indiana's electoral votes go to the blue candidate, Obama.
Digging deeper, if you click on a red county, you can see that even though they are red, some are quite close - 49.9% to 49.1%, etc. So, even if Obama didn't get a majority of a red county, he got some
votes there that contributed to his overall statewide vote and victory.
Besides apparently having good ideas and a good character, he was a great campaigner!