Question: USS "Atchison County" was Named for counties in Kansas and Missouri established in honor of a senator who passed away in which year ?

Context paragraphs:
Atchison County, Missouri: Atchison County is the northwestern-most county in the U.S. state of Missouri.  As of the 2010 census, the county had a population of 5,685.  Its county seat is Rock Port.  It was originally known as Allen County when it was detached from Holt County in 1843.  The county was officially organized on February 14, 1845 and named for U.S. Senator David Rice Atchison from Missouri.

Atchison County Raceway: Atchison County Raceway is a 1/5 mile high banked dirt oval north of Atchison, Kansas.  Phil Birkinsha, track owner, started running E-Modifieds in 2012, a class, which expanded to surrounding tracks.  Atchison County Raceway is also mistakenly called Atchison County Speedway.  Exclusive to Atchison County Raceway also is the "Ultimate Cageman Series".  The class has no rules on performance and permitted contact.  The class also features unique races like trailer smash, obstacle, and figure 8 races.  The track is currently for sale for $350,000.

Atchison County Memorial Building: Atchison County Memorial Building is a historic building located at Rock Port, Atchison County, Missouri.  It was built in 1919, and is a two-story, Classical Revival style reinforced concrete building on a raised basement.  It measures approximately 107 feet deep and 63 feet wide.  The front facade features four fluted Doric order columns that support an entabulature and frieze.  It was built with support from the Missouri General Assembly to serve as a World War I memorial and a community centre.

Atchison County, Kansas: Atchison County (county code AT) is a county located in northeastern Kansas, in the Central United States.  As of the 2010 census, the county population was 16,924.  Its county seat and most populous city is Atchison.  The county is named in honor of David Rice Atchison, a United States Senator from Missouri.

David Rice Atchison: David Rice Atchison (August 11, 1807January 26, 1886) was a mid-19th century Democratic United States Senator from Missouri.  He served as President pro tempore of the United States Senate for six years.  Atchison served as a major general in the Missouri State Militia in 1838 during Missouri's Mormon War and as a Confederate brigadier general during the American Civil War under Major General Sterling Price in the Missouri Home Guard.  He is best known for the questionable claim that for one day (March 4, 1849) he may have been Acting President of the United States.  This belief, however, is dismissed by nearly all historians, scholars, and biographers.

USS LST-60: USS "Atchison County" (LST-60) was an "LST-1"-class tank landing ship built for the United States Navy during World War II.  Named for counties in Kansas and Missouri established in honor of David Rice Atchison, a mid-19th century Democratic United States Senator from Missouri, she was the only U.S. Naval vessel to bear the name.

Atchison County: Atchison County is the name of two counties in the United States, both named for Missouri Senator David Rice Atchison:

Atchison County Courthouse: The Atchison County Courthouse, located at the southwest corner of 5th and Parallel Streets in Atchison, is the seat of government of Atchison County, Kansas.  The stone courthouse was built from 1896 to 1897 and replaced the county's first courthouse, which had been built in 1859.  County officials wanted the courthouse to resemble the Franklin County Courthouse in Ottawa, so they hired that building's architect, George P. Washburn, to design the new courthouse.  Washburn designed the building in the Romanesque Revival style.  The courthouse's design features four corner towers, including a seven-story clock tower.  The main entrance to the courthouse has a porch within a large arch; the doorway is contained in a smaller arch.  The building has a hip roof with intersecting gable dormers; the towers have pyramidal roofs.

Atchison, Kansas: Atchison is a city and county seat of Atchison County, Kansas, United States, and situated along the Missouri River.  As of the 2010 census, its population was 11,021.  The city is named in honor of David Rice Atchison, United States senator from Missouri, and was the original eastern terminus of the Atchison, Topeka and Santa Fe Railway.  Atchison was the birthplace of aviator Amelia Earhart, and the Amelia Earhart Festival is held annually in July.  Atchison is also home of Benedictine College, a Catholic liberal-arts college.

Atchison County Historical Museum: Atchison County Historical Society Museum is a museum dedicated to preserving the history of Atchison County, Kansas.  Both the city of Atchison and Atchison County, Kansas are named after United States Senator and legendary "President for a day" David Rice Atchison.

Supporting paragraphs: USS LST-60 David Rice Atchison
Answer: 1886