Arizona Gov. Jan Brewer has signed a bill into law that authorizes the construction of a fence along the state's portion of the U.S.-Mexico border, either with other states or by itself.
She signed the bill Thursday, but her spokesman, Matt Benson, declined to comment Friday on why she signed it or whether she plans to invoke the authority.
The bill does not specify a cost or make an appropriation but says the state would use donations, inmate labor and private contractors.
Brewer has asked President Barack Obama to extend a National Guard deployment along the border and for more substantial fences to block smugglers. Arizona is a major gateway for illegal immigrants and marijuana smuggling.
An existing 646-mile fence covers about 30 percent of the 2,000-mile border.