Their efforts in at least 14 states are a direct message to the federal government: If you don't take action to strengthen privacy, we will.
"We need to stand up and protect our liberty," said Republican Missouri state Sen. Rob Schaaf, author of a digital privacy bill.
Police groups, however, say the moves will in some cases hinder efforts to deter or solve crimes. "It would cripple law enforcement's ability to do investigations," said Bart Johnson, executive director of the International Association of Chiefs of Police.
Proponents say the measures will overhaul the definition of digital privacy and help increase oversight of specific surveillance tools that law enforcement agencies have been using in the states that critics say mirrors federal surveillance technology.
The bills include a Colorado proposal that would limit the retention of images from license plate readers, an Oregon bill that would require "urgent circumstances" to obtain cellphone location data and a Delaware plan that increases privacy protections for text messages.
Republican and Democratic lawmakers have joined in proposing the measures, reflecting the unusual mix of political partnerships that have arisen since the NSA revelations that began in May.
Supporters say the measures are needed because technology has grown to the point that police can digitally track someone's every move.
Devices such as license plate readers and cellphone trackers "can tell whether you stayed in a motel that specializes in hourly rates, or you stopped at tavern that has nude dancers," said David Fidanque, director of the American Civil Liberties Union of Oregon.
"It's one thing to know you haven't violated the law, but it's another thing to know you haven't had every one of your moves tracked," he said.
As for digital privacy, bills promoting broader protections against email surveillance have popped up recently in various states with varying results. One proposal became law in Texas last year, but a similar measure was vetoed in California where the governor said it was too onerous for police to follow.
But proposals focused specifically on police surveillance are a new variety.
Schaaf's proposal for a legislatively mandated ballot measure in Missouri would add electronic data to a list of property protected from unreasonable search and seizure. If it passes, it would go before voters in November.
"The people in Missouri, if they get the chance to approve it, will send a message that other states can, and must, do the same thing," Schaaf said. "We can't wait on Congress to pick up the banner."
In Indiana, legislators have put forward a bill that would ban the warrantless use of a portable device that can track cellphone movements within a mile, as well as the numbers of incoming and outgoing calls and text messages. Indiana lawmakers also want to use warrants to limit the use of tracking devices and surveillance cameras.
"You could get to the point where you're just tracking everyone's car just for the fun of it," said Republican Rep. Eric Koch.
Clatsop County, Ore., District Attorney Josh Marquis said the legislators' concerns are misplaced. He said state agencies aren't collecting the kind of metadata the NSA collects and bills curtailing the ability of local authorities to gather intelligence could do more harm than good.
Under NSA surveillance programs that NSA analyst Edward Snowden revealed, the agency sweeps up information about millions of Americans' phone calls: the number called from, the number called and the duration of the call.
That information is stored at NSA facilities until a secret court known as the Foreign Intelligence Surveillance Court gives intelligence officers permission to examine the phone call if investigators believed there was a connection to a terrorist. Another similar program examines Internet data and email traffic.
"People think of the NSA as this group of agents trotting the globe, snooping on people," Marquis said. "That's not the case. They're geeks and analysts. They don't want your data. What they're looking for is four numbers in Lahore, Pakistan."
Instead, local law enforcement agencies are using the technology to run surveillance on drug cartels or lure sex predators into online communication that leads to an arrest, Marquis said.
After months of NSA revelations, President Barack Obama last month proposed changes that would require bulk telephone data collected by the NSA to be stored outside the government to reduce the risk of abuse and put limits on the number of people who could be watched.
Still, Obama in calling for the changes Jan. 17, defended government surveillance programs.
"The reforms I'm proposing today should give the American people greater confidence that their rights are being protected, even as our intelligence and law enforcement agencies maintain the tools they need to keep us safe," he said.
But whether these proposals or any others floating around Congress will actually come to a vote is unclear. NSA surveillance opponents say that even if those measures did pass, they won't be enough to guard Americans' privacy against what they see as an over-intrusive government.
"It was a shock to (constituents) when you tell them 'this is legal,' and people say, 'No way!' " said Wisconsin Democrat Melissa Sargent, a state representative who sponsored bipartisan legislation aimed at social-media privacy and cellphone tracking.
Even some opponents concede that changes to surveillance and data privacy laws are likely, with several of them in places such as Wisconsin, Texas and Montana already passed or awaiting governors' signatures.
Increased oversight is "a reality that is coming to law enforcement," said Georgia Bureau of Investigation director Vernon Keenan. "And we can either try to stand up and fight it off, which is not possible," Keenan said, "or embrace what is reasonable."
Associated Press writers Ivan Moreno in Denver, Lisa Baumann and Rachel LaCorte in Olympia, Wash., Tom LoBianco and Charles D. Wilson in Indianapolis and David Lieb in Jefferson City, Mo., contributed to this report.
Reach reporter Nigel Duara on Twitter at http://www.twitter.com/nigelduara