As expected, unsubstantiated reports of electronic voting system malfunctions trickled into various independent monitoring organizations Tuesday, but officials acknowledge that it could be days before an accurate picture emerges of how well or poorly the e-voting systems performed.

As many as 50 million Americans across 27 states were expected to use some form of electronic voting system to cast their ballot for president before polls close later tonight. And while there have already been hundreds of reported problems associated with the systems since early voting started in some states on Oct. 18, most remain unsubstantiated.

As of 4:15 p.m. (EST) Tuesday, the online Election Incident Reporting System, a tracking system sponsored by grass-roots voter organizations such as the Verified Voting Foundation, was reporting 635 alleged incidents nationwide related to e-voting machine problems.

New York and Pennsylania accounted for the most incidents, with at least 242 reported by late afternoon. In Philadelphia, which has Pennsylvania"s largest concentration of voters, 86 incidents were reported, all of which involved voting systems that were allegedly not working properly. However, none of the reports has been independently verified.

Earlier Tuesday in Philadelphia, rumors spread quickly that e-voting machines were showing vote totals before the start of counting, prompting state Republican party officials to cry foul and threaten litigation. Those reports were false because observers misinterpreted an odometer-style vote counter that records all votes cast on each machine and is not reset for each election, said Kenneth Rapp, deputy secretary for regulatory programs for Pennsylvania.

However, at least four polling places in the city reported malfunctioning of older voting machines from Danaher Controls Inc., Doherty said.

In one precinct in Virginia, where the line of voters waiting to vote surpassed 100, only one of the eight Advanced Voting Solutions Inc. WinVote touch-screen systems was in operation, due to unidentified problems.

But most election officials in Ohio, Pennsylvania, Wyoming and Michigan said they had not received any reports of problems with any electronic or other voting systems in use. And that was on a day when state elections officials around the nation reported extremely heavy turnout.

Princeton computer science professor Edward Felton, a spokesman for Evoting-experts.com, an independent group of computer science and IT security experts, acknowledged that the reports being posted on his organization"s Web site are based on press reports and have not been independently verified.

"We disclose our sources so that readers can make up their own minds," said Felton. "Of course, the big picture will only emerge over the coming days and weeks."

At least one of the reports, however, is based on Felton"s own personal experience, he said. Felton said he arrived at the Littlebrook School polling station in Princeton, N.J., at 8 p.m. Monday and found the building open for a Boy Scout meeting. He also said four Sequoia AVC Advantage e-voting machines from had been left unattended in the school"s lobby overnight.

"Anybody who walked up had uninterrupted, private time with the machines," Felton wrote in his report of the incident. "It was clear that had somebody wanted to tamper with the machines last night, they could have done so."

Elsewhere across the nation:

- In Columbus, Ohio, overcharged batteries on Danaher Controls Inc. ELECTronic 1242 systems kept machines from booting up properly at the beginning of the day. Election workers quickly resolved the problem, and those systems were brought online. No polling place had to suspend voting because of the problem, said Jeff La Rue, a spokesman for the Franklin County Board of Elections.

- In Louisiana, state election officials received about 200 complaints of problems with machines, including two confirmed reports of Sequoia AVC Advantage voting machines in New Orleans Parish that were not working, according to Scott Madere, press secretary for the Louisiana Secretary of State. New Orleans has about 800 electronic voting machines in use, he said.

Additional problems with Election Systems & Software (ES&S) iVotronic machines occurred in Louisiana after officials improperly formatted ballots so that systems labeled nonprovisional ballots as provisional, and vice versa, Madere said. Provisional ballots are being given to voters whose registration is found to be in doubt when they go to vote.

The formatting problem will not affect how votes were recorded, and poll workers were instructed to tell voters to fill out the ballots as is. Election officials will be able to discern the difference between the two groups because there will be far fewer provisional ballots, Madere said.

- In other parts of the country, high voter turnout overwhelmed polling places that had just a few voting machines.

In Lake County, Ohio, voters were waiting for about 15 or 20 minutes to vote this morning -- a rarity in the county -- because there were not enough Sequoia Voting Systems Inc. AVC Advantage electronic voting machines to accommodate a voter turnout that was expected to approach 80 percent, said Linda Hlebak, deputy director of elections for Lake County in Painesville, Ohio.

"We knew we didn"t have enough. But we could have doubled the number of machines and still not had enough," she said.

- In heavily populated Florida, New York and California, wait times were an hour or longer.

But in Florida, where the 2000 election turned into a long-running drama that eventually was decided by the U.S. Supreme Court, there did not appear to be widespread e-voting problems by late afternoon in Miami-Dade County or Palm Beach County, said Matthew Zimmerman, a staff attorney with the San Francisco-based Electronic Frontier Foundation, who is monitoring the situation with other volunteers in Miami.

Computerworld"s Todd Weiss and Paul Roberts and Juan Carlos Perez of the IDG News Service contributed to this report.