Wilson Frost (born December 27, 1925) is a former Chicago alderman of the 34th Ward.
 In 1976, upon the death of longtime mayor Richard J. Daley, Frost declared that he was now acting mayor, based upon his interpretation of the city charter and the fact that he was serving as President Pro Tempore of the City Council.
 However, Wilson found himself literally locked out of the mayor's office—he was told that the keys could not be found.
 In a power struggle that lasted several days, the entirely Democratic city council determined that Frost was incorrect in his claim, and appointed Alderman Michael Bilandic as acting mayor instead.
 Had he been elected mayor, Wilson Frost would have been Chicago's first African American mayor.
The Jersey City 2004 mayoral special election took place on November 2, 2004.
 Democrat Jerramiah Healy won the election with 28% of the vote over his nearest rivals (Assemblyman Lou Manzo, 24%, and Acting Mayor L. Harvey Smith, 22%).
 The previous Mayor Glenn Cunningham, the first African-American Mayor died of a heart attack five months prior and L. Harvey Smith became Acting Mayor.
 There was also an election in 2005, which Healy also won.
Hazen Stuart Pingree (August 30, 1840 – June 18, 1901) was a four-term Republican mayor of Detroit (1889–1897) and the 24th Governor of the U.S. State of Michigan (1897–1901).
 A Yankee who migrated from New England, he was a Georgist social reformer who battled corporations and was an early leader of the Progressive Movement.
William Richert (October 28, 1858 – June 16, 1912) served as acting mayor of Detroit, Michigan from March 22, 1897 to April 5, 1897, following the resignation of Hazen S. Pingree.
Marcos A. Devers (born October 25, 1950) is a member of the Massachusetts House of Representatives, and a former acting mayor of Lawrence, Massachusetts.
 When Devers served as acting mayor from September to November 2001 he was the first Dominican-American to execute the role of mayor in the United States and the first Latino mayor in Massachusetts.
Joseph Rakowski is an American Democratic Party politician who served as Acting Mayor of Jersey City, New Jersey.
 He became acting mayor when he was elected to serve as City Council President of Jersey City.
 Rakowski was the third person to hold the office in the same year.
Sekesai Makwavarara is the former deputy mayor and acting mayor of Harare.
 Makwararara began her work for council in 2002 for Mabvuku as a member of the Movement for Democratic Change party.
 Initially a member of ZANU-PF, she temporarily was a member of the Movement for Democratic Change.
 During her tenure of service for the Mabvuku city council she served under deputy mayor Elias Mudzuri until she was appointed as acting mayor following the forced deposition of Mudzuri by the national government.
 After the MDC party launched a probe which identified her as being corrupt she rejoined the ZANU-PF.
 She resigned from this position in 2004.
 In 2006, she was appointed as the head of a commission that ran the Harare City Council's affairs until December 2008.
Branislav Belić (, ] or ] ; 1932 Belgrade, Kingdom of Yugoslavia – 17 July 2016 Belgrade, Serbia) was a Serbian politician.
 He was an Acting Mayor of Belgrade following the 2008 election.
 He served as an interim Chairman of the Assembly as the oldest member.
 Previously this seat, which is also a seat of the acting mayor, was held by Zoran Alimpić.
 Acting mayors were necessary in the period until the election of the new one, due to the death of the elected mayor Nenad Bogdanović.
 His term ended with election of Dragan Đilas.
Marilyn Roman (born March 1936) is an American educator and Democratic Party politician who served as Acting Mayor of Jersey City, New Jersey.
 As City Council President, she became Acting Mayor succeeding Gerald McCann after his removal from office.
 Roman was the first woman to hold the office of mayor in the history of Jersey City.
Michael Barnes is the mayor pro tempore of Charlotte, North Carolina.
 He also served as acting mayor for a short time following the resignation of former mayor Patrick Cannon, who was arrested on March 26, 2014 for corruption charges.
 Barnes immediately became acting mayor upon Cannon's resignation.
 The City Council was then required to appoint a mayor to serve out the remainder of Cannon's term (through Dec. 2015).
 On April 7, the council voted to appoint Dan Clodfelter, a state senator, as the new mayor.

Question: Who was the acting mayor of Detroit when Hazen S. Pingree resigned from office in 1897?
Answer: William Richert