Question: Who was president when statehood was awarded to the territory that includes the county where Union Township is found?

full_context: Document 1: Iowa: Almost immediately after achieving territorial status, a clamor arose for statehood. On December 28, 1846, Iowa became the 29th state in the Union when President James K. Polk signed Iowa's admission bill into law. Once admitted to the Union, the state's boundary issues resolved, and most of its land purchased from the Indians, Iowa set its direction to development and organized campaigns for settlers and investors, boasting the young frontier state's rich farmlands, fine citizens, free and open society, and good government.
Document 2: Ohio: On February 19, 1803, U.S. President Thomas Jefferson signed an act of Congress that approved Ohio's boundaries and constitution. However, Congress had never passed a resolution formally admitting Ohio as the 17th state. The current custom of Congress declaring an official date of statehood did not begin until 1812, with Louisiana's admission as the 18th state. Although no formal resolution of admission was required, when the oversight was discovered in 1953, Ohio congressman George H. Bender introduced a bill in Congress to admit Ohio to the Union retroactive to March 1, 1803, the date on which the Ohio General Assembly first convened. At a special session at the old state capital in Chillicothe, the Ohio state legislature approved a new petition for statehood that was delivered to Washington, D.C. on horseback. On August 7, 1953 (the year of Ohio's 150th anniversary), President Eisenhower signed a congressional joint resolution that officially declared March 1, 1803, the date of Ohio's admittance into the Union.
Document 3: Howard County, Iowa: Howard County is a county located in the US state of Iowa. As of the 2010 census, the population was 9,566. The county seat is Cresco. The county was founded in 1851; it was named for General Tilghman Ashurst Howard, a Representative of Indiana.
Document 4: Harrison Township, Howard County, Indiana: Harrison Township is one of 11 townships in Howard County, Indiana, United States. As of the 2010 census, its population was 9,489 and it contained 4,169 housing units.
Document 5: Union Township, Howard County, Indiana: Union Township is one of eleven townships in Howard County, Indiana, United States. As of the 2010 census, its population was 1,029 and it contained 419 housing units.
Document 6: Union Township, Hendricks County, Indiana: Union Township is one of twelve townships in Hendricks County, Indiana, United States. As of the 2010 census, its population was 1,856.
Document 7: History of Idaho: When President Benjamin Harrison signed the law admitting Idaho as a U.S. state on July 3, 1890, the population was 88,548. George L. Shoup became the state's first governor, but resigned after only a few weeks in office to take a seat in the United States Senate.
Document 8: Howard, South Dakota: Howard is a city in Miner County, South Dakota, United States. The population was 858 at the 2010 census. It is the county seat and most populous city in Miner County.
Document 9: Union Township, Parke County, Indiana: Union Township is one of thirteen townships in Parke County, Indiana, United States. As of the 2010 census, its population was 1,562 and it contained 1,451 housing units.
Document 10: Union Township, Vanderburgh County, Indiana: Union Township is the most sparsely populated of the eight townships in Vanderburgh County, Indiana, USA. As of the 2010 census, its population was 292 and it contained 227 housing units. This is largely due to the entire township being located within the Ohio River Floodplain.
Document 11: Indiana: In order to decrease the threat of Indian raids following the Battle of Tippecanoe, Corydon, a town in the far southern part of Indiana, was named the second capital of the Indiana Territory in May 1813. Two years later, a petition for statehood was approved by the territorial general assembly and sent to Congress. An Enabling Act was passed to provide an election of delegates to write a constitution for Indiana. On June 10, 1816, delegates assembled at Corydon to write the constitution, which was completed in 19 days. President James Madison approved Indiana's admission into the union as the nineteenth state on December 11, 1816. In 1825, the state capital was moved from Corydon to Indianapolis.
Document 12: Center Township, Howard County, Indiana: Center Township is one of eleven townships in Howard County, Indiana, United States. As of the 2010 census, its population was 45,275 and it contained 22,736 housing units.
Document 13: Harrison Township, Union County, Indiana: Harrison Township is one of six townships in Union County, Indiana, United States. As of the 2010 census, its population was 416 and it contained 182 housing units.
Document 14: Corydon, Iowa: Corydon is a city in Wayne County, Iowa, United States. The population was 1,585 in the 2010 census, a decline from 1,591 in the 2000 census. It is the county seat of Wayne County.
Document 15: Des Moines, Iowa: On September 22, 1851, Des Moines was incorporated as a city; the charter was approved by voters on October 18. In 1857, the name ``Fort Des Moines ''was shortened to`` Des Moines'', and it was designated as the second state capital, previously at Iowa City. Growth was slow during the Civil War period, but the city exploded in size and importance after a railroad link was completed in 1866.
ground_truth: President James K. Polk
sub_queries: Union Township >> located in the administrative territorial entity Answer: Howard County
Howard County >> located in the administrative territorial entity Answer: Iowa
who was president when Iowa became a state Answer: President James K. Polk