Fewer than one out of 10 of the city's active Democrats and Republicans went to the polls in Tuesday's primary election, likely the lowest figure in decades, according to veteran poll-watchers.

"We haven't seen the final numbers, but from the numbers I've seen, it clearly is the lowest turnout in my experience," said Frederick L. Voigt, chief counsel to the city commissioners, who began working on elections in the city Law Department in 1969.

Voigt and others cited multiple reasons for voters' lack of interest: On the Democratic ballot, an assortment of low-profile races for judgeships and city controller; on the Republican ballot, no contests at all; no ballot questions for independent voters; and virtually no television advertising by any campaigns.

"No contest at the top of the ticket, no TV - that's what drives turnout," Voigt said. It's like Pavlov's dogs - we're conditioned to respond to signals, and the signal that indicates an election is coming up is TV [advertising]. If no TV, what you get is the absolute minimum number of people who vote out of habit."

It's too early to come up with a final turnout figure because the city hasn't collected data cartridges from all the voting machines distributed for Tuesday's election.

The latest unofficial count showed 84,577 voters visited the polls, in addition to 1,002 absentee ballots, a figure that could increase slightly, as overseas and military ballots are given extra time to arrive.

But for now, that makes 85,579 voters in Tuesday's primary out of 869,839 "active" Democrats and Republicans - registered voters who have gone to the polls at least once in the last five years.

That's a 9.8 percent total. If you compared the turnout to the total number of registered Democrats and Republicans, 925,634, the turnout percentage would be lower still - 9.2 percent.

City Commissioner Al Schmidt, the only Republican on the three-member panel that runs city elections, said the turnout in the 2009 primary, with the same offices at issue, was about 13 percent.

But 2009 featured a five-way contest for the Democratic nomination for district attorney. This year, incumbent Seth Williams was unopposed, as was the Republican candidate, Daniel Alvarez.

Schmidt was on the ballot in that race as the GOP's unopposed candidate for controller. "I'm familiar with how difficult it is to get voters interested in candidates they never heard of for offices they never heard of," he said.

Though the city describes its current count as just 96 percent complete, the numbers are unlikely to change significantly.

Most of the still-uncounted voting cartridges were in machines that were not used on Election Day, according to Gregory Irving, the city's acting voter registration administrator. Many polling places get multiple machines because of high voter volume in previous elections, but if voters can be accommodated on a single machine, the extra machines are never used.

The numbers confirm what members of one election board after another reported Tuesday, that turnout was the lowest they'd ever seen.

A closer look at the election results makes the turnout look even weaker - about 20 percent of the people who turned out to vote apparently ignored the races at the top of the ticket.

As of Wednesday evening, the machine totals showed 62,414 votes cast in the Democratic contest for city controller, which drew more votes than any other Democratic race. That figure represents just 7.7 percent of the city's active Democrats.

Contact Bob Warner at 215-854-5885 or warnerb@phillynews.com.