I did a little digging on electoral trends, taking 1960 as the arbitrary starting point of the modern era. Looking at these past 11 elections, I count as a safe party state those that have voted for the same party at least 8 of the 11 times.
5 states plus DC are safe Democratic states (having voted for the Democrats 8+ of 11 times):
DC, Maryland, Massachusetts, Minnesota, New York, and Weat Virginia. In the 2004 election they will give 71 electoral votes to the Democrats.
20 states are safe Republican states (having voted Republican 8+ of 11 times)
Alabama, Alaska, Arizona, Colorado, Florida, Idaho, Indiana, Kansas, Mississippi, Montana, Nebraska, New Hampshire, North Carolina, North Dakota, Oklahoma, South Carolina, South Dakota, Utah, Virginia, and Wyoming. In the 2004 election, these states will give 154 electoral votes to the Republicans.
Not a single state of the old Confederacy is a Democratic stronghold, while 6 of 11 former Confederate states are safe for Republicans. Clearly the south is the weakest region for presidential Democrats, and therefore the hardest for non-southern Democrats to win. Being that Republicans need only pick up 116 tossup electors while Democrats need 199, it is clearly much harder for Democrats to pick up the White House without southern support than it is for the Republicans.
I’m not sure there is a southern monopoly on power, for years Tip O’Neill of Massachusetts was the Speaker. Indeed, from the start of McCormack’s reign in 1961, only Jim Wright and Newt Gingrich were southern, so 8 years of the past 42 does not a dynasty make.
In this time, only Howard Baker, Trent Lott, and now Frist have been Southern majority leaders, so again 8+ years of 42 is hardly domination.