If you drive in Seattle, there is a good chance the police department knows where your car has been at least once during the past three months.

Seattle police recorded license plates on 72 percent of Seattle’s streets while searching for stolen cars and chronic parking offenders during an 86-day period this past summer. In all, police made more than 1.6 million scans of more than 600,000 unique plates, according to an analysis of a department database.

Nearly half of city streets received at least three visits from the license-plate scanners between May 11 and Aug. 5, according to the analysis.

Citywide, the scans yielded 1,858 stolen cars and illegal parkers.

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The analysis provides the first snapshot of the Seattle Police Department’s (SPD) license-plate-scanner program. It has come under scrutiny amid concerns about how much information government agencies collect.

The program works like this: A dozen police vehicles travel the streets equipped with cameras that automatically scan plates and compare them to lists of stolen cars and people with at least four unpaid parking tickets. If there is a hit, the officer responds. Even if there is not, the record is stored for three months in an SPD database that can be used for future criminal investigations.

Critics, including the American Civil Liberties Union (ACLU), complain that retaining the records on vehicles’ whereabouts could potentially lead to abuse.

To better understand the SPD’s database, The Seattle Times in late July requested a copy of it.

Police agencies in some states have denied those types of requests from reporters.

But the SPD responded, providing a massive electronic file that contained records for the three previous months.

The numbers show the SPD scanned an average of nearly 19,000 plates per day during the time, including roughly 23,000 on weekdays, 11,000 on Saturdays and 8,000 on Sundays.

Twenty-one percent of the scans did not have a location, because the GPS was not picking up a signal or had not been activated.

The locations of the rest spanned the entire city, with some exceptions.

“You’re trying to get to every corner of the city and have that visible presence,” said police spokesman Sean Whitcomb, “whether it’s in a parking-enforcement role or a 911 emergency-response role.”

Among the most frequently scanned areas were highly trafficked parts of the city: Capitol Hill, downtown, Sodo, the Chinatown International District, and parts of Queen Anne and Ballard.

The largest clusters of scans appeared near the SPD’s East Precinct (12th Avenue and East Pine Street) and parking-enforcement headquarters (Airport Way South and South Walker Street).

Several other clusters also stood out, including near Golden Gardens Park, where four separate officers scanned plates on 32 different days.

Whitcomb said they may have decided to look there for stolen cars, which are often dumped in popular parking lots.

One officer scanned license plates down to Fife on two different occasions, once up to Snohomish and, on 34 days, outside the Seattle Police Athletic Association on East Marginal Way South.

Whitcomb said it’s common for officers to leave the cameras on as they help with out-of-city investigations or take part in training.

“My understanding is that it’s actually just on, chewing up license-plate data because you just never know when or where you’re going to come across a stolen car,” he said. “It’s a technology that’s kind of always running.”

Brian M. Rosenthal: 206-464-3195 or brosenthal@seattletimes.com. On Twitter @brianmrosenthal. Justin Mayo: jmayo@seattletimes.com