The main difference between bicameral and unicameral legislatures is that bicameral legislatures pass laws out of two chambers while unicameral legislatures do so out of one. At the federal level around the world, unicameral legislatures outnumber bicameral legislatures 115 to 64.
The federal government of the United States follows a bicameral system by dividing Congress into the Senate and the House of Representatives. The U.K. Parliament with its House of Lords and House of Commons is also bicameral. The Riksdag of Sweden and the National People's Congress of the People's Republic of China are examples of unicameral assemblies.
Unicameral legislatures tend to pass laws quickly, and they offer greater accountability because there is no opposing side that can be blamed for mistakes or deadlock. Single-chamber governments can sometimes be run with fewer representatives, thereby saving taxpayers money. In contrast, bicameral legislatures facilitate discussion over important issues, restrain majority parties, block the passage of frivolous laws and deliver enhanced oversight over the executive branch. Many dual-chamber governments were formed to ensure voter representation across different social classes, ethnic groups or regional interests.
Within the United States, only Nebraska possesses a unicameral state legislature. Unicameralism has been proposed in the states of New York, Maine and Minnesota.