If a search algorithm is Google's most closely guarded secret, the company's second biggest secret might be its employee numbers.

On any given weekday morning, traffic snarls in all directions on Highway 101 as an untold number of employees flock to Google's global headquarters in Mountain View's North Bayshore.

Untold, because exactly how many people are working in these offices has always been something the company is loath to reveal, ever since it located here in 1999. On numerous occasions, Mountain View's elected officials have pressed Google for its headcount for traffic planning purposes, but the company has always equivocated, said former Mayor Jac Siegel.

"You'd ask them specifically for an answer, and they'd blow smoke at you," he said. "At best, they'd give a confusing answer, but you'd never get a specific employee number."

"I always wondered why this number is so confidential," said Councilwoman Margaret Abe-Koga. "They might give us a ballpark number, but they would never say exactly how many folks are working there."

Now Mountain View officials appear to be helping the company keep the employee numbers a secret. For the first time, Google is providing regular reports to Mountain View on its headcount figures, but the city is withholding this information from the public, on Google's recommendation.

In response to a records request filed by the Voice, city officials consulted at least twice with Google officials to decide what information should be treated as trade secrets and redacted from public documents. This could be a violation of California Government Code, which prohibits outside groups from preventing the release of public information.

"Public agencies are not supposed to allow a third party to control the disclosure of public records," said Nikki Moore, an attorney with the California News Publishers Association who specializes in the state's public records laws. "Once Google discloses this to a government agency, it doesn't have a right to dictate whether the information is public."

Last year, Google representatives agreed to provide headcount information to Mountain View. At the time, the company's real estate team was focused on winning city approvals for the company's new showplace headquarters at Charleston East, which is scheduled for completion next year.

Before granting the approvals, city officials wanted some kind of assurance that Google's expansion wouldn't worsen traffic congestion in North Bayshore, at least, not until a series of nearby road improvements were finished. For that reason, Google's team promised to allow a third-party auditor to survey its offices to produce an annual report on the Mountain View campus' headcount, including employees, consultants and interns. If the auditor found Google had increased its employee numbers, then Mountain View could block the Charleston East campus from opening.

In March, the first of these reports was delivered to Mountain View, and the Voice requested a copy. The city turned over a heavily redacted report with dozens of paragraphs -- and even some entire pages -- blanked out. Among the privileged information, the city withheld the auditor's methodology for counting employees and Google's internal systems for tracking employees.

The whole point of the report was also redacted the city removed any mention of Google's current employee headcount and the old number to which it was being compared. Across the board, all this information was redacted under a California Government Code section that exempts disclosure of public records related to trade secrets for corporate developments.

In an interview, Mountain View Public Works Engineer Ed Arango admitted the city was "conservative" in deciding what to withhold. Last month, he said he reviewed the Google reports with the city attorney's office.

After striking out some language, they sent a copy to Google for further revisions, he said. Certain systems mentioned in the reports were unique to Google, and the city couldn't identify them without the company's assistance, Arango said.

"We provided Google an opportunity to review it, and they were more conservative and they wanted more redactions," he said. "This was new to us, and I didn't know what was proprietary information."

Public Works Director Mike Fuller disputed the notion that the city was ceding its responsibility on public records. The process was "collaborative," he said.

After the Voice pressed the city to explain why so much information was being withheld, the city attorney's office promised to revisit the reports and disclose more information.

In that second review, city officials again allowed Google to participate in deciding what information should be redacted, Arango said.

The second round of reports released more information, although various sections remain redacted. In particular, city officials still insist that Google's current employee numbers in North Bayshore must not be made public.

However, the city did reveal Google's employee headcount as of 2016 -- 26,143. That number is being used as the baseline to compare the company's current employee numbers.

While city officials won't reveal Google's current workforce numbers, they can at least give assurances that it's under 26,143.

Google officials did not immediately respond to requests for comment.