Nevada Senator Joe Hardy, R-Boulder City, listens to testimony from economic experts on the Senate floor during the second day of a special session at the Nevada Legislature, in Carson City, Nev., on Thursday, Sept. 11, 2014. Lawmakers are considering a complex deal to bring Tesla Motors to Nevada. (AP Photo/Cathleen Allison)

Calling it one of the most important pieces of legislation in Nevada history, Gov. Brian Sandoval has signed into law an unprecedented package of incentives to bring Tesla Motors' $5 billion battery factory to the state.

The Republican governor put his signature to the measure shortly after the state Legislature controlled by Democrats unanimously approved the package late Thursday night.

The deal includes tax credits and other incentives worth up to $1.3 billion for the electric-car maker to build the biggest lithium battery factory in the world about 15 miles east of Sparks.

Sandoval told reporters and lawmakers crowded into his Capitol office: "This is as big as it gets."

He was joined by Tesla Vice President Diarmuid (DEER'-mihd) O'Connell, who said the project will allow the company to carry out its mission of promoting sustainable transportation by creating a mass market for electric vehicles.

  • Nevada Senator Michael Roberson, R-Las Vegas, listens to testimony from economic experts on the Senate floor during the second day of a special session at the Nevada Legislature, in Carson City, Nev., on Thursday, Sept. 11, 2014. Lawmakers are considering a complex deal to bring Tesla Motors to Nevada. (AP Photo/Cathleen Allison)

  • Nevada Tax Director Chris Nielsen, right, answers questions on the Senate floor during the second day of a special session at the Nevada Legislature, in Carson City, Nev., on Thursday, Sept. 11, 2014. Lawmakers are considering a complex deal to bring Tesla Motors to Nevada. Steve Hill, with the Governor's Office of Economic Development is at left. (AP Photo/Cathleen Allison)