Colorado restricts illegal immigrants from receiving in-state tuition. Nebraska requires verification of immigration status to obtain public benefits. In Tennessee, knowingly presenting a false ID card to get a job is a misdemeanor.

A supporter of Arizona's immigration law puts his views on display outside the U.S. District Court in Phoenix. (Joshua Lott, Reuters / July 15, 2010)

Arizona's strict new law has generated the most controversy, but there are hundreds of immigration-related laws on the books across the country. The laws regulate employment, law enforcement, education, benefits and healthcare.

The U.S. Department of Justice filed a lawsuit last week to stop the Arizona law from taking effect July 29, saying that immigration policy is a national responsibility and "a patchwork of state laws will only create more problems than it solves." But according to experts, that is precisely what exists.

In fact, the number of immigration-related laws and resolutions enacted by states surged to 333 last year, up from 32 in 2005, according to the National Conference of State Legislatures. And during the first three months of 2010, lawmakers introduced more than 1,000 bills and resolutions, though it's too early to tell how many will become law. Bills on topics such as employment verification and driver's license requirements are on the table in 45 states.

"Lawmakers are frustrated with the federal inaction," said Ann Morse, program director for the organization's Immigrant Policy Project. "Until the federal government acts, states will still see this as an area where they see the need to play a leadership role."

Already, the organization says, legislators in five states - South Carolina, Pennsylvania, Minnesota, Rhode Island and Michigan - have introduced similar bills to Arizona's SB 1070, which requires police to check the immigration status of people they lawfully stop and suspect are in the country illegally. As of last month, six resolutions had been passed in five states regarding SB 1070 - four opposing it and two supporting it. The law has prompted lawsuits, protests and boycotts.

"I frankly understand the position Arizona finds itself in," said Virginia state Sen. John Watkins. "We all live in elected republics. The pressure gets put on, especially in tough economic times."

Watkins said he is frustrated that Congress cannot get beyond the politics on immigration. "The federal government has walked away from its responsibility. They are the reason states are scrambling."

In a speech this month at American University, President Obama called for comprehensive immigration reform but did not set any timetable for legislation to be introduced.

States have a long history of enacting immigration laws. In 1996, after Congress denied welfare to most legal immigrants, states stepped in with laws to provide safety net services. And following the Sept. 11 attacks, state lawmakers passed bills aimed at protecting national security.

"People were concerned about dangerous immigrants in their midst, and they thought they should take matters into their own hands," said Muzaffar Chishti, director of the Migration Policy Institute's office at New York University School of Law.

The increase in state laws parallels the changing settlement patterns of illegal immigrants. Between 1990 and 2008, illegal immigration slowed significantly in California but grew in Georgia, North Carolina and other states, according to a 2009 Pew Hispanic Center report.

"These are not your typical immigrant-receiving states, so they are not accustomed to having large immigrant populations," said Michele Waslin, senior analyst at the Immigration Policy Center. "They are struggling with how to deal with new populations."

Citizen groups also noticed the demographic change and the federal government's inaction.

Carol Helm, retired from the oil and gas industry, started an organization in 2004 called Immigration Reform for Oklahoma Now. She began working with state lawmakers to draft legislation that would restrict the rights of illegal immigrants, who were arriving in large numbers in search of jobs. Lawmakers passed the bill in 2007, limiting the ability of illegal immigrants to get public assistance and giving police the authority to check the immigration status of anyone arrested.

"The constituents' voices were heard," Helm said. "They are the ones who actually pushed it."

Not all of the laws are anti-immigrant, said Suman Raghunathan, immigration policy specialist at the Progressive States Network. Ten states have passed laws to allow undocumented college students to pay in-state tuition, and several have expanded access to state-funded health benefits and improved enforcement of wage and hour laws.

"There is an alternative way to look at this ... for legislators to realize the value of integrating and welcoming immigrants and immigrant families to their states," she said.

Washington state Rep. Sharon Tomiko Santos said that although immigration falls under the federal government's jurisdiction, states are responsible for illegal immigrants living within their borders. States have to pay the bulk of the cost for education, healthcare and incarceration of illegal immigrants, and they must help newcomers integrate.

Santos said the conflicting laws from state to state can create confusion. For example, a company may have offices in two states - in one that requires employment verification and in one that doesn't. "It is exactly those kinds of issues that need to be worked out at the federal level so that there is no question across the 50 states as to what the rules are," she said.

Santos said states generally agree that the enforcement of civil immigration policy is a federal responsibility. "It is not a responsibility that states necessarily want," she said.

But Federation for American Immigration Reform President Dan Stein said immigration policy is inevitably a partnership between states and the federal government. The states are "the keys to the kingdom" - where immigrants get identification documents, services and jobs, he said.

"If you try only to control immigration at the border ... it's an exercise in futility," he said. "National immigration policy can only be carried out with the participation of the states."