Thanks for posting the complete list of dates, FelizLA.
The numbers below represent the progression or retrogression, in days, of priority dates from the Feb 15 update to the March 15 update. They are in their February chronological order, since the March update is more suspect.
As in the past, there appear to be at least two standards being applied: a standardized target-based criterion for most DOs (July 20 and June 30), and variable dates for DOs that fall outside those targets (presumably based on PD). The retrogression we're seeing in the new update seems to affect both groups quite differently.
The following had standardized dates in both updates, and uniformly retrogressed 20 days. (The exception is Des Moines, which had been at 9/1/07, but has joined the main group of DOs).
Des Moines IA -63
Agana GU -20
Albany NY -20
Albuquerque NM -20
Buffalo NY -20
Charleston WV -20
Chicago IL -20
Chula Vista CA -20
Cincinnati OH -20
Cleveland OH -20
Columbus OH -20
Dallas TX -20
Detroit MI -20
El Paso TX -20
Fort Smith AR -20
Fresno CA -20
Greer SC -20
Harlingen TX -20
Honolulu HI -20
Houston TX -20
Indianapolis IN -20
Jacksonville FL -20
Kansas City MO -20
Louisville KY -20
Milwaukee WI -20
New York City NY -20
Omaha NE -20
Pittsburgh PA -20
Portland ME -20
Reno NV -20
Rochester NY -20
Sacramento CA -20
Salt Lake City UT -20
San Antonio TX -20
San Bernardino CA -20
San Diego CA -20
San Francisco CA -20
Santa Ana CA -20
Spokane WA -20
Syracuse NY -20
Wichita KS -20
Yakima WA -20
The following all posted dates prior to July 20 in the February update, but still fell within July. They all joined the June 30 group for the March update. Note that these dates all retrogress.
Saint Albans VT -15
Anchorage AK -13
Oklahoma City OK -11
Casper WY -9
Denver CO -9
Saint Paul MN -8
Charlotte Amalie VI -7
Portland OR -7
The remaining dates were all June or earlier in the February update, and did not have standardized processing estimates. In the March update, a few of these have joined the June 30 group, but most of them still have variable dates rather than standardized ones. More interesting, all of them have crept ahead instead of retrogressing (suggesting again that this is the only group that is tracking actual PDs). The BIG exception to this is Los Angeles, which retrogressed more than any other DO. Speculation is that they're basing the processing estimate on time from PD to oath, but for the great majority of DOs no conclusion can be drawn from this.
Los Angeles CA -80
San Juan PR 14
Boise ID 8
West Palm Beach FL 7
Manchester NH 0
Atlanta GA 10
Providence RI 10
Newark NJ 12
Las Vegas NV 5
Seattle WA 18
Helena MT 0
Phoenix AZ 8
Saint Louis MO 32
Cherry Hill NJ 30
Tampa FL 31
Boston MA 25
Christiansted VI 43
Tucson AZ 8
Miami FL 5
Baltimore MD 23
Charlotte NC 17
San Jose CA 14
Memphis TN 23
Dover DE 25
Philadelphia PA 30
New Orleans LA 32
Norfolk VA 0
Charleston SC 47
Hartford CT 92
Orlando FL 136
Washington DC 24