Allegheny county had a problem for over ten years in the 1990s over assessments. In the mid 1990s for the first time since the Great Depression, Allegheny County came under Republican rule (The Chief of the previous Democratic County Board of Commissioners had made a stupid statement about not needing black votes, so the blacks revolted and refused to vote for him, leaving the GOP win for one four year term). As that GOP term was ending Allegheny County then adopted a new form of Government permitted under Pennsylvania "Home Rule" Law (Which permitted local Government to form their own form of government rather than a state derived form).
As part of the Home Rule Charter Allegheny County Dropped the previous three man County Commissioner's board and opt for a Executive with a County Council. The Council has always been Democratic, with a minority of Republicans on it. The first race for County Executive was between Cyril Wecht (Who had more than enough enemies) and Rodney as the GOP candidate. The Blacks were still mad at the Democrats so avoided voting for Wecht (Who Barely lost the election even with that opposition). Rodney was for reform of taxes, i.e abolishment of Property taxes (More to ease business property tax rates, but that was NEVER mentioned, senior citizens unable to pay their taxes on their homes were the example always cited)
Anyway the GOP won office by saying they would abolish property taxes. When that failed, they lost what support they had and the Democrats won back the office. The GOP County Commissioners imposed a "Freeze" on assessments, when that was ruled by the Courts to violate State Law, the GOP tired other ways to end Property taxation, but the problem was Property Taxes is the fairest way to asses taxes. If to high, property values DROP to compensate for the excessive rates, if to low property values goes UP to reflect the low tax rate. Thus in a County where you have over 100 different taxing bodies, the only way to do any form of fair taxation is on value of property. As I said once people accepted that the GOP was out and the Democrats were back in.
Anyway, as part of the solution to the property tax mess created by the GOP in the 1990s, County Council adopted a policy of yearly assessments. As part of that Assessment system ALL PROPERTIES IN ALLEGHENY COUNTY WERE REACCESSED IN 2002 (and reassess annually ever since). As part of that Assessment it was decided to put the accessed houses on line, since that would be the easiest method for people to get the information on they new assessments and look at comparative housing to make sure it was fair. Thus the on line system you see (came out of Carnegie Mellon University, CMU for short).
I would like to say it was the first in the Country, but others had it before, it is a nice system (NOT adopted by any other County in Pennsylvania let alone the rest of the Country). The biggest dispute at present is people who do NOT want their property on line. At present that is NOT possible and defeats the whole purpose of being on line i.e. compare your property to others of the same type AND your neighbors. People don't want this information on line BUT IT WAS ALWAYS A PUBLIC RECORD. A few years ago the local Federal Judges asked that their properties be taken off, and the County did do that, but all that did was increase the calls by others that they want they name off line for "they own protection" (Remember ALL of this is Public Record, so if someone wants to find out the name of where someone lives, all he or she had to do is go to the local Courthouse and find that information, in the over 200 years it has been public record I have NEVER heard or read of a case where the Public Record was used to commit a violate Criminal act against someone and the same is true of the on line system since 2002).
For more on Wecht and his problems (Which still continue he is under Federal indictment)
http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=102x3159246