Maryland joins at least 17 other states and 140 local jurisdictions that have passed similar legislation, according to a legislative analysis.
Similar proposals have been introduced in the Maryland legislature since 2007, but none made it through both houses. The measure will protect transgender people from housing, public accommodation and employment discrimination.
Baltimore City became the first jurisdiction in Maryland in 2002 to pass legislation protecting transgender rights. Montgomery County passed similar legislation in 2007, Howard County in 2011, and most recently, Hyattsville in 2013.
The governor handed the pen he used to sign the transgender law to Sen. Richard S. Madaleno, a Montgomery County Democrat who fought for eight years to convince his colleagues to pass it.
"It provides important protections for people who are just trying to live their lives," Madaleno told The Baltimore Sun. "They won't get thrown out of their homes, out of their jobs, out of a restaurant, just for being who they are."
Conservative opponents have launched a petition drive, hoping to collect enough signatures to put the transgender law up for a referendum vote in November, the Sun reports. Opponents have dubbed it the "Bathroom Bill" because it protects a person's right to use restrooms for the gender with which he or she identifies. They fear the law could protect male predators who sneak into women's restrooms, a charge the LBGT community has described as fear-mongering.
The measure was one of scores of bills the governor was scheduled to sign during the last scheduled public signing ceremony of his eight years as governor, The Baltimore Sun says.
Among the legislation also to receive the governor's signature are bills outlawing so-called "revenge porn" – posting intimate pictures on the Internet as a way of getting back at a former spouse or lover – and overhauling the state's speed camera law to add new safeguards for drivers from malfunctioning systems.
Related: Maryland Senate Passes Bill to Protect Transgender Rights
Transgender Rights Bill Awaits Final Vote in Maryland House