The Census Bureau reported that Orleans Parish (effectively, the city of New Orleans) led the nation in population growth in percentage terms in 2006-7.
The 14% growth sounds great. The raw number of 29K sounds good too ... but compared to what?
The report doesn't mention the tables on this page that you have to tunnel through links to get at. These show a drop in the population of the New Orleans metropolitan area of 286K since 2000.
Yes, some of that is coming from the surrounding parishes, but the bottom line is that from 10 to 22 months after Katrina (the time frame covered by the Census Bureau) only about 10% of the people who fled the storm moved back.
Non-statisticians may be inclined to extrapolate that and claim that in 10 years New Orleans we'll be back. Unfortunately, that isn't the way the growth works.
In order for growth to carry New Orleans population back to what it was before, it will have to follow an approach path that is asymptotic to (something like the) old population levels. That asymptotic behavior requires growth rates that start high and tale off towards zero. This means that next year the growth of Orleans Parish will probably be lower.
The size of that drop-off is the next big problem. If growth rates stay close to 10%, then New Orleans will recover quickly.
In fact if growth rates only decrease by a tenth every year, then it might recover the half of the population it lost to Katrina in about 12 years (assuming that growth rates bottom out at the replacement rate of 2%).
But, do we really expect growth rates to decline that slowly?
I'm speculating, but I think rates might drop more quickly.
The sad thing is because of the multiplicative aspects of the underlying math, it doesn't take much of a decline in growth rates in the 2nd year for New Orleans to never recover.
In terms of raw numbers, if population growth in New Orleans comes in a year from now at 25K, we're looking at 2 generations for New Orleans to recover. At 24K, a quarter of the people who left will never, ever, come back. At 22K it will be half.
Check back here in March 2009 for an update.