The secretary of state is an official in the state governments of 47 of the 50 states of the United States, as well as Puerto Rico and other U.S. possessions. In Massachusetts, Pennsylvania, and Virginia, this official is called the secretary of the commonwealth. In states that have one, the secretary of state is the chief clerk of the state and is often the primary custodian of important state records. In the states of Alaska, Hawaii, and Utah, there is no secretary of state; in those states many duties that a secretary of state might normally execute fall within the domain of the lieutenant governor. Like the lieutenant governor, in most states, the secretary of state is in the line of succession to succeed the governor, in most cases immediately behind the lieutenant governor. In three states with no lieutenant governor (Arizona, Oregon and Wyoming) as well as the U.S. territory of Puerto Rico, the secretary of state is first in the line of succession in the event of a gubernatorial vacancy.

Currently, in 35 states, the secretary of state is elected, usually for a four-year term. In others, the secretary of state is appointed by the governor with confirmation with the state's respective Senate; Florida, Oklahoma, Texas, and Virginia are among the states with this practice. In three states, the secretary of state is elected by the state legislature; the General Assembly of Tennessee meets in joint convention to elect the secretary of state to a four-year term, and the Maine Legislature and New Hampshire General Court also select their secretaries of state, but to two-year terms. The longest serving state secretary of state in history was Thad A. Eure of North Carolina, who served from 1936 until 1989.

Secretaries of state, or those acting in that capacity, belong to the National Association of Secretaries of State.