Jefferson Parish actually got pretty lucky. They were nowhere as badly hit as Slidell and New Orleans, or the coastal Parishes etc. Many of the houses in the parish didn't flood at all.
Interesting; seems as though the media gave the wrong impression/misreported *again*... 
Is Jefferson slightly higher above sea-level than the rest of the area then?
The Mississippi River flows primarily east to west (with loops) from south of Baton Rouge (blob on west edge of map) to just east of New Orleans where it turns southeast towards the birdfoot delta.
The main part of New Orleans (NO) is on the east bank (that is, north of the river). The river surface is above sea level as are the banks (and the river levee). This is where the original city is, including the French Quarter.
The ground slopes downward toward the north and Lake Pontchartrain - which is actually a bay. Marshlands along the shoreline of the lake have been drained to permit development and a lake levee built. Removing the water has caused the soil to compact and subside so that this area is quite a bit below sea level (I think 10 to 15 feet).
There is a small sliver of New Orleans (Orleans Parish is coterminous) on the west bank, southeast of the center of the city. This is also on higher (above sea level) ground along the river. This area, known as Algiers is the first part of the city that has been opened up for re-occupation and has electricity, water, and sewer.
Jefferson Parish (JE) is west and south of Orleans Parish. The main area including Metairie, Kenner, and Louis Armstrong Airport is on the east bank, immediately west of New Orleans.
Metairie is immediately west of New Orleans, and has a similar elevation boundary. The 17th Street Canal is on the parish boundary. It breeched on the east side, and flooded New Orleans. Had the west side breeched it would have flooded Metairie. As it was, some water worked its way around the southern end of the canal and into Metairie, though this was blocked off fairly quickly, in part because it was toward the high end. Jefferson Parish probably had less wind damage because it further west from the path of the hurricane.
The canal is not a navigation canal, but a drainage canal. Water is pumped up to the canal, which ordinarily flows northward into Lake Pontchartrain.
Jefferson Parish also includes an area on the west bank (south of New Orleans), including suburbs of Westwego, Marrero, and Gretna.
Further south in Jefferson Parish is Lafitte (LA). It received a storm surge during Hurricane
Rita. In the news this was reported as Jefferson Parish flooding, even though the area is at the head of a southward facing bay. Wind flow around a northern hemisphere cyclone is counterclockwise, with the strongest winds usually on the northeast. During Katrina, the winds here were mostly from the north, which tended to push or at least hold the storm surge out. During Rita, this was on the northeast side of the storm track for several days, which pushed the storm surge up, even though it was 100+ miles from the storm center.
Grand Isle (GI) is a barrier island. Its only connection to the rest of Jefferson Parish is by water. The land route is from the west (follow the red lights toward the northwest). It regularly recieves hurricane damage, and had lots of wind damage during Katrina.
Plaquemines Parish (PL) is southeast of New Orleans along the Missisissippi River to the birdfoot delta. Settlement is right along the river, between two levees. Storm surge animations basically show the parish disappearing except for this thin strip. The levees overtopped during Katrina trapping water in between, until they were breached to permit draining.
St Bernard Parish (SB) is east of New Orleans. It sustained a much more direct hit, plus a storm surge.
St Tammany Parish (ST) is north of Lake Pontchartrain. There are two causeways, one connecting Metairie with Covington (lights in SW corner of parish), and another northeastward to Slidell (SL) in the southeast corridor. This is a twin span carrying I-10 east to Mississippi, Mobile and into Florida. It is about 20 feet above the water, and many of the segments were displaced or dislodged. Temporary repairs are being made now to open one span.
St Tammany had lots of wind damage (many pine trees), and Slidell had flooding due to a mainly direct hit. There was also some flooding along the shoreline.
Mississippi is east of St Tammany, and took a direct hit from the storm surge which was directly on shore. Gulfport (GU) and Biloxi (BI) are along the coast. Mobile Bay (Alabama) is the inlet in the extreme NE corner of the map. There was also a lot of wind damage that extended inland.
During the 1990s, New Orleans was one of the slowest growing metropolitan areas (slower than Detroit and Philadelphia, faster than Pittsburgh and Cleveland), extremely atypical for the south.
Orleans had a 5.5% decline, Jefferson and St Bernard were about even, and St Tammany a 44% increase (to 200K+).
Baton Rouge has the advantage of being large enough to be able to house lots of people on a temporary basis, and close enough (80 miles) to commute from on a temporary basis. I don't know that long term it will have the jobs. If oil companies move offices from New Orleans, it will be to Houston. The port can't move, nor can the cultural activities. People without jobs will move to Houston, Dallas, Atlanta, and Florida.
The rental market in Jefferson Parish and on the west bank should be really tight, as well as in St Tammany, especially after the I-10 causeway is repaired. I'd expect St Tammany to continue to grow, and also attract people who are more flood wary. There might be some smaller regional companies that move some operations to Baton Rouge.
East Baton Rouge Parish could become the most populous in the state, but it might have happened without the hurricane. Now it might occur by 2010 instead of 2020.
1990 to 2003 population in 1000s.
EBR 380 412
Orleans 496 469
Jefferson 448 452
