Direct floor supervision over distribution clerks has lightened up considerably with the advent of extensive automation and computerization.
Two things there....automation should have reduced the overall numbers of employees, yes or no.
As far as first line supervisor, I am not going to dispute your numbers, which are probably correct, however, I think one has to look at the entire administrative structure per carrier. IMO, delivering mail is not rocket science and why there is a huge bureauracy concerns me. Here are some comparison numbers from Poatal Magazine:
USPS EMPLOYEE STATISTICS FROM 2000 - 2010
2000 2010 -/+ Percentage
USPS Headquarters 2279 2924 +28%
Inspector General 664 1151 +73%
USPS HEADQUARTERS TOTALS 2943 4075 +38.46%
USPS Field Support / Inspection Service (Field) 9756 7173 -26%
USPS FIELD TOTALS 9756 7173 -26.47%
Postmasters (Installation Heads) 26121 23324 -11%
Supervisors / Managers 38797 27848 -28%
USPS SUPERVISORY TOTALS 64918 51172 -21.17%
Tech Personal 9959 5907 -41%
Clerks / Nurses 282147 161607 -43%
Mail Handlers 60851 49674 -18%
City Carriers 241079 197105 -18%
Motor Vehicle 9347 7614 -19%
Rural Carriers 57111 67434 +18%
Maintenance 42284 37513 -11%
Vehicle Maintenance 5546 4977 -12%
USPS CRAFT EMPLOYEES TOTALS 708324 531831 -24.91%
USPS is probably a bit more computerized than most people imagine, or can imagine.
Headquarters grew mostly through shutting down field management units such as regional headquarters, Districts, MSCs and a wide variety of other management type operations.
The net number of "executives" and specialists in that top layer is thinner now than at any time in USPS or Post Office Department history.
USPS has its own economists, CPAs, lawyers (to bring suit against people who don't pay or who fail to properly haul mail ~ that's all private contracts BTW ~ or to aid DOJ lawyers in putting away bad guys).
The Inspector General, that looks like a budding growth industry, carved a chunk out of other management type structures including the Postal Inspection Service. It's a mix of cops and analysts for the most part ~ got to know an awful lot of them simply by being one of the world's foremost experts in mailing practices).
My primary area for many years was in the field of Classification (pricing and collections for you folks in the private sector) ~ we went from having about 1300 people available to us in 1978 to about 347 in 2004. A lot of that reduction was made possible through automation, mechanization, computerization and robotics.
Excess personnel position were transferred to other jobs closer to the primary mission ~ moving the mail.
For most of the period you were looking at the number of mail pieces handled per person increased substantially, denoting massive productivity increases, and the density of supervisory personnel of any kind decreased substantially throughout the system.
During the current downturn field supervisory positions have been cut like there's no tomorrow. Some guy retires his job is gone.
What I hear about Headquarters you don't want to know but it's brutal!