Anton Eugene Armstrong (born April 26, 1956) is the conductor of the St. Olaf Choir as well as the Harry R. and Thora H. Tosdal Professor of Music at St. Olaf College of Northfield, Minnesota in the United States.
 Armstrong became the fourth director of the St. Olaf Choir in 1990, continuing the tradition begun by the choir's founder F. Melius Christiansen in 1911, sustained and developed by his son, Olaf Christiansen, and strengthened and enhanced by Kenneth Jennings.
 Armstrong also teaches conducting in the Sacred Music department at Luther Seminary.
 He also conducts some pieces in "Northfield Youth Choirs".
St. Olaf College is a coeducational, residential, four-year, private liberal arts college in Northfield, Minnesota, United States.
 It was founded in 1874 by a group of Norwegian-American immigrant pastors and farmers, led by Pastor Bernt Julius Muus.
 The college is named after the King and the Patron Saint Olaf II of Norway and is affiliated with the Evangelical Lutheran Church in America.
Magnum Chorum is a choral ensemble based in the Twin Cities of Minnesota.
 Magnum Chorum performs sacred choral music in cathedrals and sanctuaries throughout the Midwest.
 The 65 voice auditioned choir presents concerts, commissions new sacred works, makes recordings, and provides music for worship.
 Founded in 1991 in the choral tradition of St. Olaf College, membership was originally limited to St. Olaf graduates, but since 2005, auditions are open to singers devoted to excellence in choral music.
 Magnum Chorum’s name is intended to convey the importance of the choir in expressing the divine and infinite through voice, music, and text.
The St. Olaf Orchestra, is the touring symphony orchestra of St. Olaf College, Northfield, Minnesota.
 In addition to its annual domestic tours, the St. Olaf Orchestra has performed in Scandinavia, central and eastern Europe, China, and, most recently, South America.
 It has appeared in some of Europe’s finest concert halls and performed with some of the world’s most noted conductors and artists.
 It is currently under the direction of Steven Amundson and has been featured at national, regional, and statewide conventions, as well as multiple appearances on National Public Radio.
The O. E. Rølvaag House was the home of Ole Edvart Rølvaag (1876-1931), Norwegian-American novelist and professor at St. Olaf College.
 The home is located at 311 Manitou Street in Northfield, Minnesota, United States.
 Rølvaag wrote most of his works in this house, which is near St. Olaf College, where he taught.
Northfield is a city in Dakota and Rice counties in the State of Minnesota.
 The city is mostly in Rice County, with a small portion in Dakota County.
 The population was 20,007 during the 2010 census.
This list of St. Olaf College people contains links to Wikipedia articles about notable alumni and other people connected to St. Olaf College, a private liberal arts college in Northfield, Minnesota.
St. Olaf Auditorium, also known as the St. Olaf Opera House and Auditorium, is a historic building located in St. Olaf, Iowa, United States.
 The city was able to complete the auditorium in 1939 with the assistance of the Public Works Administration (PWA) and labor provided under the aegis of the Works Progress Administration (WPA).
 Both are New Deal programs that sought to relieve the economic effects of the Great Depression.
 The building is a two-story structure composed of native rubble limestone that follows the PWA Moderne style.
 It has served as a community center that has hosted a variety of social activities, including recreational, athletic, cultural, educational, and civic functions.
 The auditorium was used occasionally for vaudeville and minstrel shows.
 It was listed on the National Register of Historic Places in 1994.
Inglebrikt was the first child of Johan and Ingeborg Grose.
 His father, Johan had arrived in the United States during 1854 from Stetten, then a part of Prussia.
 His mother, Ingeborg emigrated to the United States from the western Norway during the same year.
 His parents were married in Wisconsin in 1860 and moved to Kenyon, Minnesota, where Grose was born in 1862.
 Grose attended primary school in Kenyon, after which he traveled to St. Olaf College in Northfield, Minnesota.
 While at St. Olaf College, Grose married Mary Jacobson.
 He attended Luther College in Decorah, Iowa, after which he returned to St. Olaf College as a Professor.
The St. Olaf Band, an ensemble of approximately 90 musicians, is the touring concert band of St. Olaf College, Northfield, Minnesota.
 The band was founded in 1891, and holds the honor of being the first music organization established at St. Olaf.
 F. Melius Christiansen assumed leadership of the band in 1903.
 In 1906, Christiansen took the St. Olaf Band on tour to Norway to play for King Haakon VII, making it the first college music ensemble to conduct a tour abroad.

Question: What is the population of city in which St. Olaf College is located? 
Answer: 20,007