It's the year of the super PACs in Philadelphia.

Campaign finance filings yesterday show three super PACs have raised twice as much as the six Democratic mayoral candidates in 2015.

The super PACs raised about $9.1 million this year, while the candidates themselves, bound by city contribution limits, raised about $4.1 million.

By far the biggest player is American Cities, the committee funded by three wealthy pro-school choice donors, which supports state Sen. Anthony Williams' campaign. It raised $6.8 million, 97 percent of that from the three partners of the Susquehanna International Group.

Building a Better Pa, the super PAC supporting Jim Kenney, reported raising about $1.4 million. Roughly a third, $450,000, came from electricians' Local 98. And in a fascinating twist, $725,000 came from a New Jersey fund associated with the carpenters union. The Philadelphia carpenters are supporting Williams. More on that here.

Oh yeah, the candidates

Reports from the candidates show a two-tiered race. Williams, Kenney, and former District Attorney Lynne Abraham each raised more than a million bucks this year. Former PGW executive Doug Oliver raised around $40,000 and former state Sen. Milton Street did not file his report by the time the board of election offices closed Friday.

Former City Solicitor Nelson Diaz was somewhere between the two tiers. He reported raising $394,000 in 2015, about a quarter of that a personal loan to the campaign. Abraham loaned her campaign $122,000.

Williams reported having the most cash on hand for the stretch run -- $623,000 -- while Kenney reported $310,000 on hand. Both figures were as of last Monday.

The big question as the race comes to a close is whether American Cities, which has purchased over $900,000 in TV ad time for the final week, stays with positive ads about Williams or attacks Kenney.