NEW YORK (CNN/Money) - There's a reason it's called the promised land.

California can count four of the top ten richest cities in America, according to data released Tuesday by the Census Bureau. In addition, seven of the top ten are located west of the Mississippi, while 9 of the 10 poorest cities in the country are located either on the Mississippi or east of it.

So does that mean the West is getting richer while the East slides into decay? Not quite.

The East boasts nine of the 10 richest counties.

It would be tempting to say that affluence in western cities tends to stay closer to downtown while the eastern elite flee to the suburbs, but demographers at the Census Bureau caution against such conclusions.

The sample of this year's study, which only looked at cities and counties with a population of 250,000 or more, isn't wide enough to draw larger trends. For that, we'll have to wait for next year's study, which will survey all cities and counties with a population of 65,000 or more.

In the meantime, here's a look at how the largest cities and counties stacked up, according to the Bureau's 2004 American Community Survey: