Question: When was the county, where Shelby Airport is located, established ?

Context paragraphs:
Shelby–Cleveland County Regional Airport: Shelby–Cleveland County Regional Airport (ICAO: KEHO, FAA LID: EHO) is a public use airport located three nautical miles (6 km) southwest of the central business district of Shelby, in Cleveland County, North Carolina, United States.  It is owned by the City of Shelby and was formerly known as Shelby Municipal Airport.  It is home to the Shelby Composite Squadron of the Civil Air Patrol, the USAF Civilian Auxiliary.

Shelby Community Airport: Shelby Community Airport (FAA LID: 12G) is a privately owned, public use airport located two nautical miles (4 km) west of the central business district of Shelby, in Richland County, Ohio, United States.

Toole County, Montana: Toole County is a county located in the northern portion of the U.S. state of Montana.  As of the 2010 census, the population was 5,324.  Its county seat is Shelby.  The county was established in 1914 from parts of Hill County and Teton County and was named after Joseph Toole, the first and fourth governor of Montana.  Its northern boundary is the Canada–United States border south of Alberta.

Central Shelby Historic District: Central Shelby Historic District is a national historic district located at Shelby, Cleveland County, North Carolina.  It encompasses 229 contributing buildings in the central business district and surrounding residential areas of Shelby.  The district is centered on the Cleveland County Courthouse (1907) and public square, established in 1841.  The district includes representative examples of Colonial Revival and Bungalow / American Craftsman architectural styles.  The district includes the separately listed courthouse, Masonic Temple Building, and Webbley.  Other notable buildings include the Webb House, Wells House, Fulenwider-Ebeltoft House, Dr. S. S. Royster House, Bateman House, Washburn Block, city hall and firehouse (1911), Royster Building (1910), First Baptist Church, Ascension Lutheran Church (1932), and Southern Railway Freight Depot (c. 1920).

General DeWitt Spain Airport: General DeWitt Spain Airport (FAA LID: M01) is a civil, public airport located five miles (8 km) northwest of the central business district of Memphis, a city in Shelby County, Tennessee, United States.  It is owned and operated by the Memphis - Shelby County Airport Authority.

Charles W. Baker Airport: Charles W. Baker Airport (FAA LID: 2M8) is a civil, publicly owned airport.  It is located four miles (6 km) southwest of the central business district of Millington, TN, a city in Shelby County, Tennessee, United States.  It is only 10 miles (16km) from downtown Memphis, TN.  It is owned and operated by Memphis - Shelby County Airport Authority.  It also immediately adjacent to Memphis Motorsports Park.

Shelby County Airport (Illinois): Shelby County Airport (FAA LID: 2H0) is a public airport located three miles (4.8 km) west of the central business district (CBD) of Shelbyville, a city in Shelby County, Illinois, USA.

Shelby County Airport (Alabama): Shelby County Airport (ICAO: KEET, FAA LID: EET) is a public use airport located four nautical miles (7 km) southeast of the central business district of Alabaster, a city in Shelby County, Alabama, United States.  It is owned by the Shelby County Commission.  The airport is situated in the city of Calera, Alabama.

Shelby County Airport (Missouri): Shelby County Airport (FAA LID: 6K2) is a public airport located 1 mile (2 km) northwest of Shelbyville, in Shelby County, Missouri, USA.

Shelby Airport: Shelby Airport (IATA: SBX, ICAO: KSBX, FAA LID: SBX) is a county owned airport two miles north of Shelby, in Toole County, Montana.  The National Plan of Integrated Airport Systems for 2011–2015 called it a "general aviation" airport.

Supporting paragraphs: Shelby Airport Toole County, Montana
Answer: 1914