On September 30, 2014, Governor Brown signed into law a bill making California the first state in the nation to ban single-use plastic bags. Consumers may either use their own reusable bags or pay at least ten cents for a paper bag or a multi-use plastic carrier that meets a set of state durability standards. More than 100 California cities and counties have already passed regulations banning plastic bags. (See list.) These existing regulations may still be enforced, but the law preempts municipalities from adopting new regulations of single-use plastic bags, meaning those adopted on or after September 1, 2014, and restricts amendments to existing regulations. Grocery stores, big bulk retail stores that sell groceries and pharmacies statewide must phase out the use of plastic bags by July 1, 2015. The ban will expand to cover convenience stories and liquor stores one year later, on July 1, 2016.