In 1853, Rice entered local politics, winning election to Boston's Common Council.
 He served for two years, the second as council president.
 In 1854, he also served as president of Boston's School Committee.
 Rice was elected mayor of Boston in 1856 (as a "Citizens" candidate opposed to the Know Nothings), and served two one-year terms.
 During his tenure, an agreement was reached between the city, state and owners of a tidal waterworks concerning development of the Back Bay, then a smelly swamp laden with trash and sewage.
 The agreement authorized the construction of what is now Arlington Street, and specifically set aside as parkland the area between it and Charles Street, which is now the Boston Public Garden.
 He later sat on the committees responsible for the commissioning and installation of the statues of George Washington and Charles Sumner in the Public Garden.
 He also authorized construction of the city's first hospital, and repurposed the city's almshouse on Deer Island for use as an insane asylum and workhouse, the state having taken over care of the indigent.

Rice participated in the founding of the Republican Party in Massachusetts.
 He was elected to the U.S. House of Representatives in 1858, and served four terms, from 1859 to 1867.
 He was chairman of the Committee on Naval Affairs from 1863–65.
 He was a conservative Republican, opposed to Radical Republican positions on the abolition of slavery, and was considered by labor interests to favor positions of the "moneyed class".
 He introduced the Crittenden Compromise to the House in January 1861; his speech on this last-ditch attempt to prevent civil war received a lukewarm reception.
 After the war, he was elected as a Third Class Companion of the Military Order of the Loyal Legion of the United States in recognition of his support for the Union.
In 1853, Rice entered local politics, winning election to Boston's Common Council.  He served for two years, the second as council president.  In 1854, he also served as president of Boston's School Committee.  Rice was elected mayor of Boston in 1856 (as a "Citizens" candidate opposed to the Know Nothings), and served two one-year terms.  During his tenure, an agreement was reached between the city, state and owners of a tidal waterworks concerning development of the Back Bay, then a smelly swamp laden with trash and sewage.  The agreement authorized the construction of what is now Arlington Street, and specifically set aside as parkland the area between it and Charles Street, which is now the Boston Public Garden.  He later sat on the committees responsible for the commissioning and installation of the statues of George Washington and Charles Sumner in the Public Garden.  He also authorized construction of the city's first hospital, and repurposed the city's almshouse on Deer Island for use as an insane asylum and workhouse, the state having taken over care of the indigent.
Rice participated in the founding of the Republican Party in Massachusetts.  He was elected to the U.S. House of Representatives in 1858, and served four terms, from 1859 to 1867.  He was chairman of the Committee on Naval Affairs from 1863–65.  He was a conservative Republican, opposed to Radical Republican positions on the abolition of slavery, and was considered by labor interests to favor positions of the "moneyed class".  He introduced the Crittenden Compromise to the House in January 1861; his speech on this last-ditch attempt to prevent civil war received a lukewarm reception.  After the war, he was elected as a Third Class Companion of the Military Order of the Loyal Legion of the United States in recognition of his support for the Union.
Alexander H. Rice