In the United States, 45 of the 50 states have an office of lieutenant governor. In two of the 45 states, the speaker of the upper house of the state legislature serves in such a capacity. In most cases, the lieutenant governor is the highest officer of state after the governor, standing in for that officer when they are absent from the state or temporarily incapacitated. In the event a governor dies, resigns or is removed from office, the lieutenant governor typically becomes governor.
In 25 states, the governor and lieutenant governor are elected on the same ticket, ensuring that they come from the same political party. In the remaining 18 states, they are elected separately and, thus, may come from different parties. The lieutenant governor is also frequently the presiding officer of the upper house of the state legislature, similar to the vice president of the United States. Among the seven states without a separate, full-time office of lieutenant governor, two states have a post of lieutenant governor that is filled by the highest officer of the state Senate. In Tennessee, the full title of the leader of the Senate is " lieutenant governor and speaker of the Senate". In West Virginia, the title of lieutenant governor is assigned by statute to the Senate president. With the exception of Arkansas, Georgia, Idaho, Tennessee, Texas, Virginia, Washington, and West Virginia, every state has had a female lieutenant governor or equivalent - although Mona Pasquil briefly acted as lieutenant governor of California between Abel Maldonado and John Garamendi.
In Maine, the presiding officer of the State Senate assumes the governor's office upon a vacancy, while in New Hampshire, the presiding officer of the State Senate assumes only the governor's powers and duties (becomes acting governor) upon a vacancy. In the remaining three states – Arizona, Oregon, and Wyoming – the secretary of State becomes governor upon the office's vacancy.
The U.S. territories of American Samoa, Guam, Northern Mariana Islands and the Virgin Islands have the office of lieutenant governor. In Puerto Rico, the appointed secretary of State becomes governor upon the office's vacancy while the chief of Staff is typically the highest office after the governor.
Lieutenant governors are the only officials with specific duties and powers in two branches of state government: the executive and legislative branches. More than half of the NLGA members preside over their state senate. Most pursue legislative initiatives; many testify locally and in Washington D.C. in various capacities; some serve on the governors’ cabinets; and others maintain varied portfolios of duties. In many states, the duties of lieutenant governor are increased by legislation to include the lieutenant governor on state boards, commissions and task forces. "
Since Alaska, Hawaii, and Utah do not have a secretary of State, the lieutenant governor performs the duties generally granted to that office. In New Jersey, the governor must appoint the lieutenant governor to head a cabinet-level department or administrative agency within the state government's executive branch—but not to the post of state attorney general,  Lieutenant Governor Kim Guadagno also served as secretary of State from 2010 to 2018. The lieutenant governor of Texas plays an active role as presiding officer of the State Senate and is often rumored to be more powerful than the state governor.  The lieutenant governor of Vriginia also serves as the president of the Senate, as do about half the lieutenant governors. 
The positions are sometimes criticized for lacking duties and power and described by political insiders as "get up, read the paper, see if the governor is dead, if not, go back to sleep".  In the 2010 election for the lieutenant governor of Rhode Island, 40% of the vote was won by a perennial candidate who wanted to abolish the office,  saying "If you open up the dictionary to ‘ sinecure,’ you have a picture of the lieutenant governor of Rhode Island".
In November 2005, New Jersey voters approved a constitutional amendment to create the office of lieutenant governor, which became effective with the 2009 general election. The state's first lieutenant governor took office in January 2010.
The position was created in response to the unusual circumstances surrounding the aftermath of the 2001 gubernatorial election. At the time Senate President Donald DiFrancesco was acting as governor following the resignation of Christine Todd Whitman earlier that year. DiFrancesco's term as Senate president expired one week before the governor-elect assumed office in January 2002, necessitating a special arrangement in which the party leaders of the incoming Senate took turns serving as acting governor (each serving a few days) until Jim McGreevey was sworn in. All told, five people had served as governor or acting governor in the space of one year.
In Arizona, the secretary of state is the first in line to succeed the governor in the event of death, disability, resignation, or removal from office. The line of succession also includes the attorney general, state treasurer and superintendent of public instruction. 
The gubernatorial line of succession is set forth in the state constitution, at Article V, Section 8a. It defines who may become or act as the governor of Oregon upon the incapacity, death, resignation, or removal from office (by impeachment and subsequent removal or recall) of a sitting governor. The current chain of succession is: secretary of State, State treasurer, president of the State Senate, speaker of the House of Representatives. When a governor leaves office, the next available elected individual in the succession becomes governor until the next general biennial election, when a governor will be elected to either serve out the last two years of a regular term or a new four-year term.  See: line of succession. In 2007, legislation was proposed to establish an office of lieutenant governor. 
The highest-ranking officer after the governor of Puerto Rico is the Chief of Staff who is appointed by the governor himself rather than elected. In terms of line of succession, the secretary of State of Puerto Rico acts as acting governor when the governor is temporarily disabled or unable to discharge his duties. If there is a permanent vacancy in the governorship, the Constitution of Puerto Rico establishes that the secretary becomes governor for the remainder of the term. The Secretary of State also serves as acting governor whenever the governor is temporarily not present in Puerto Rico, with territorial law also establishing a line of succession for when both the governor and the secretary are unable to perform their duties.
- List of current United States lieutenant governors
- List of female lieutenant governors in the United States
- State constitutional officer (United States)
- National Lieutenant Governors Association
- South Carolina will switch to same-ticket following the 2018 elections.
- New Jersey State Constitution (1947), Article V, Section I, paragraph 10 (as amended, effective January 17, 2006)
- Texas Observer: Who Runs Texas
- "Archived copy". Archived from the original on 2013-11-06. Retrieved 2011-12-23.
- Marinucci, Carla (January 22, 2011). "Gavin Newsom faces political challenges in new job". The San Francisco Chronicle.
-  Archived August 26, 2011, at the Wayback Machine.
- See: Arizona#State executive branch.
- See: Governor of Maine#Succession.
- "Office of the President of the Senate". Maine State Legislature. Retrieved November 13, 2017.
- See: New Hampshire#Branches of government.
- "Proposes amendment to Oregon Constitution to create elective office of Lieutenant Governor". Oregon State Legislature. Archived from the original on 2011-06-11. Retrieved 2007-04-21.
- See: Wyoming#State law and government.
- The Book of the States 2015, Duties of Lieutenant Governors Table 4.14. The Council of State Governments. http://knowledgecenter.csg.org/kc/content/book-states-2015-chapter-4-state-executive-branch