Photos of your license plate taken by police cameras can track where you’ve been, where you shop, and who you visit.

NBC 7 Investigates first revealed the extent of license plate snooping two years ago when we confirmed that the San Diego Sheriff’s Department had stored photos of 8 million license plates, many of them multiple photos of the same vehicle in different locations.

Our investigation confirmed that local law enforcement agencies have at least 100 license plate readers (LPRs).

Those cameras, many of them mounted on police vehicles, read thousands of plates every day. By taking multiple photos of the same vehicles in different locations, law enforcement can create a sort of digital road-map of your whereabouts.

But critics tell NBC 7 Investigates they are concerned with law enforcement sharing this information with other agencies.

Dave Maass with the Electronic Frontier Foundation (EFF) obtained documents from the San Diego Police department confirming SDPD shares license plate data with more than 500 local, state and federal agencies.

“It’s really alarming that San Diego Police has just been sharing (that information) widely, not even knowing they have the power to shut it off," said Maass. "There are police officers in rural Georgia who are able to just log into that system, and look up just about anybody in San Diego's driving patterns, 24-7, with very little oversight."

The Federal Office of the Inspector General and the San Diego Sector of the U.S. Border Patrol are also on SDPD’s data sharing list.

That's a big concern for critics like Pedro Rios of the American Friends Service Committee, who says local police should not cooperate with the Trump Administration’s crackdown on undocumented immigrants.

"Because there's a lack of confidence and a lack of trust already with police departments, this cements the idea that police are working against the community, and not safeguarding their rights," Rios said.

San Diego Police initially said they have no control over which agencies can access their license plate data. But NBC 7’s media partner, the Voice of San Diego found that law enforcement can limit data sharing.

For example, the San Diego County Sheriffs department shares its license plate data with only two departments: San Diego Police and Carlsbad Police. But the Sheriff's office appears to be the exception.

Maass is concerned about what happens when federal agencies, whose enforcement priorities sometimes conflict with California’s laws and priorities, obtain the license plate data.

“Are they looking at it for drug enforcement purposes that are not consistent with California law? We just don't know, and I don't think the San Diego Police Department knows either," Maass told NBC 7 Investigates.

In an email to NBC 7 Investigates, a spokesperson for the San Diego Police department said it "...uses License Plate Readers and shares information with other law enforcement agencies because it helps all of us solve and prevent crime. In an effort to keep people safe, we use technology to be adaptive and stay a step ahead of crime."

The department also said license plate readers helped detectives in its Northern Division find the suspects responsible for a series of vehicle break-ins and burglaries, leading officers to recover some of the victims' stolen property.