While the early history of the Mayors of New Orleans offers an important understanding of the roots of the position, the period following Union occupation of Louisiana in 1862 through the early twentieth century witnesses the period in which the office of Mayor developed into a more modern incarnation as the duties dictated to the Mayor changed under various Charters.

The appointment of Etienne de Bore in 1803 established the office of Mayor of New Orleans following the Louisiana purchase. For the next nine years, the Mayor was appointed by Governor Claiborne. When Louisiana became a state in 1812, the first regular election saw Nicholas Girod became the fifth Mayor of New Orleans.

The 1857 City Charter dictated "that the mayor shall be at least thirty years of age, ten years a citizen of the State and five years a citizen of the city; and shall have the qualifications required for the members of the House of Representatives of the State." Earlier laws limited the Mayor's term of office to two years. After civil government was restored, the Mayor continued to be elected on a biannual basis until the charter of 1882 changed the term of office to four years.

Initially, the charter vested executive power in "one mayor, four recorders, one treasurer, one comptroller, one surveyor, one street commissioner, a board of assessors, and a board of supervisors of assessments" (City Charter, 1857). Legislation enacted in 1870 shifted control to the Mayor and a group of seven Administrators. The Charter required these men to compose a written report of their respective departments at the end of each month. This division of authority created the Administrators of Finance, Commerce, Improvements, Assessments, Police, Public Accidents, and Water Works & Public Buildings.

The City Charter named the Mayor as the chief executive of the city and the "ex officio justice and conservator of the peace." The Mayor further held the power of veto over legislation passed by the City Council. If the Mayor returned objectionable legislation within five days of receiving it, the legislation then met a vote from the City Council, two-thirds of whom could override the veto. The Mayor could call a meeting of the City Council whenever he felt the need, or when five councilmen requested one. Other duties throughout the 19th and beginning of the 20th centuries include the duty of the Mayor to send copies of legislation passed by the Council to relevant parties, to sign bonds of the city related to consolidated debt, to be an elector in matters relating to city-held stock, to raise mortgages, and to create and use of the city seal on official documents.

City laws gave the Mayor the power to issue a number of different permits for markets and places of entertainment. Various ordinances gave the Mayor power to license bakeries, coffee houses, theaters, balls, a number of other businesses, vehicles, liquor, gunpowder sales, and prostitutes also fell under those things requiring mayoral permission. Under ordinance 228, A.S., an ordinance passed in July 1870, the Mayor gained permission, at his discretion, to grant free permits for businesses using less than fifty dollars of capital, assuming the person applying was "unable to earn a living by ordinary labor."

The office of the Mayor changed dramatically during and following the Civil War as a number of military commanders took charge of the city. The Mayor's earlier duties, as listed in the 1857 City Charter, included hiring and firing police officers, policemen, and watchmen, but The Metropolitan Police act, approved March 5, 1869, severely limited the Mayor's control over the police force. It prohibited the mayor from selecting members of the police or from disbanding them. In 1877, ordinance 3889 restored control to the Mayor and the Administrator of Police. Act Number 63 of 1888 established a Police Board in which the Mayor was the presiding officer and commander in chief of police. The roles of the Mayor in relation to the police force changed in scope as the Mayor's power was deemed more or less threatening.

The increased responsibilities and duties for the Mayor evidence progress being made in nineteenth century New Orleans. Following the Civil War, Ordinance 1011, A.S. of August 1871 granted the Mayor permission to select a druggist to distribute free medicine to poor citizens of New Orleans. Other charity ordinances emerging in the 1870s ordered the Mayor to make monthly visits to "the Boys' House of Refuge, the Insane Asylum, the Asylum for the Aged and Infirm, the Parish Prison, etc., to examine the condition of said institution (ordinance 4956, A.S., March 1879)." City history and education also began to become important tasks of the Mayor throughout the 1870s. Ordinance 1035, A.S. of August 1871 declared the Mayor should be in charge of appointing a keeper of the City Archives, while ordinance 1966, A.S. in January 1873 put the Mayor in charge of a city library.

The changes in executive power reflected changing needs of the city as it developed and progressed. By 1896, power became centralized "in one Mayor, one Comptroller, one Treasurer, one Commissioner of Public Works, one Commissioner of Police and Public Buildings and one City Engineer." The Mayor was also given the duty to report city officials who committed crimes while in office. Following accusations in 1894 that John Fitzpatrick did not follow his duty as Mayor by suspending an official on charges of bribery, the 1896 City Charter required this duty and made failure to comply subject to impeachment. The 1857 Charter required the Mayor to report to the City Council on the condition of the city "from time to time," but this requirement became more stringent in 1896 and required the Mayor make a monthly report to the Council.

The Charter of 1912 provided for a commission form of government with a mayor and four commissions elected at-large to four year terms. The mayor headed the department of public affairs. The city council voted on the heads of the the rest of municipal government, including finance, public safety, public utilties, and public property. Additionally, the mayor lacked veto power.

The Louisiana State Constitutional Amendment of 1950 authorized the creation of a home-rule charter for the city of New Orleans. The Charter of 1954 is currently in effect. It implemented the mayor-council form of government and granted the responsibilities to the city of public safety, public sanitation, and public property. It also created the position of the Chief Administrative Officer who is appointed by the mayor and under their supervision. Since 1954, various mayor's have created new departments, boards, and commissions that fall under the Office of the Mayor. Some of these include the Office of Economic Development, Office of Policy Planning and Analysis, Office of Environmental Affairs, Office of International Relations, various community and civic improvement organizations, and public safety committees.