Question: The largest county in Oklahoma by area, gets its name from the broad rolling hills and rolling tallgrass prairie and Cross Timbers encompassing the county and surrounding areas, including portions of Mayes, Tulsa, Washington and Kay Counties, was created in what year?

Context articles: Skiatook Lake
Southeast Kansas
Osage Plains
KTRL (FM)
Tallgrass Prairie Preserve
Nine Mile Prairie
Osage Hills
Midewin National Tallgrass Prairie
Tallgrass Prairie National Preserve
Osage County, Oklahoma

Skiatook Lake is a federally-owned and operated reservoir located in Osage County, Oklahoma, 4 mi west of the town of Skiatook, 11 mi east of Hominy, Oklahoma and about 18 mi from Tulsa.
 The Skiatook Dam is located on Hominy Creek, 14 miles upstream of the confluence of Hominy and Bird Creeks.
 The project purposes include flood control, water quality, water supply, recreation, and fish and wildlife management.
 The cities of Skiatook, Sand Springs, Sapulpa, and Tulsa use Skiatook Lake as a municipal water supply.
 Gentle rolling hills of Blackjack and Post Oak interspersed with Tallgrass prairie surround the lake.
 The lake is under the management of the U.S. Army Corps of Engineers, Tulsa District.
Southeast Kansas is a region of the U.S. state of Kansas.
 It can be roughly defined by Woodson County in the northwest, Bourbon County in the northeast, Cherokee County in the southeast, and Montgomery County in the southwest.
 Geographically it is dominated by a broad rolling landscape located between the Flint Hills to the west and includes the Ozarks to the southeast.
 Some notable towns there include Pittsburg, Parsons, Coffeyville, Independence, Chanute, Fort Scott, and Iola.
 The region has a land area of 13,624.13 km² (5,260.30 sq mi) and a 2000 census population of 180,815 inhabitants.
 It has 6.43% of the state's land area and 6.726% of its population.
 It is dominated by a broad rolling landscape that includes the Ozarks.
 It receives more precipitation than any other part of Kansas.
 Southeast Kansas is located in the tallgrass prairie ecosystem of North America.
 Originally inhabited by several Native American tribes, frontier towns largely dependent on cattle ranching, and mining, were wracked by violence over the issue of slavery both before and during the American Civil War.
 Southeast Kansas offers one of the premier reconstructions of early life in the United States Army at Fort Scott National Historic Site.
The Osage Plains are a physiographic section of the larger Central Lowland province, which in turn is part of the larger Interior Plains physiographic division.
 The area is sometimes called the Lower Plains, North Central Plains, and the Rolling Plains.
 The Osage Plains, covering west-central Missouri, the southeastern third of Kansas, most of central Oklahoma, and extending into north-central Texas, is the southernmost of three tallgrass prairie physiographic areas.
 It grades into savanna and woodland to the east and south, and into shorter mixed-grass prairie to the west.
 The Osage Plains consist of three subregions.
 The Osage Plains proper occupy the northeast segment.
 Although sharply demarcated from the Ozark uplift, the Plains are nonetheless a transitional area across which the boundary between prairie and woodland has shifted over time.
 In the central portion of the physiographic area lies the second subregion, the Flint Hills, commonly called "The Osage" in Oklahoma.
 This large remnant core of native tallgrass prairie is a rocky rolling terrain that run from north to south across Kansas and extends into Oklahoma.
 To the west and south of these hills are the Blackland Prairies and Cross Timbers.
 This vegetatively complex region of intermixed prairie and scrubby juniper-mesquite woodland extends into north-central Texas.
 Bluestem prairies and oak-dominated savannas and woodlands characterize the natural vegetation in the Cross Timbers.
 Much of the area has been converted to agriculture, although expanses of oak forest and woodland are still scattered throughout the eastern portion of the subregion.
KTRL–FM 90.5 is a noncommercial public radio station licensed to Tarleton State University in Stephenville, Texas.
 KTRL broadcasts to a 10–county area of the Cross Timbers just southwest of Fort Worth, Texas, covering a population of about 200,000 people.
 The station is partnered with Texas A&M's KAMU-FM 90.9 FM, bringing a mix of public radio and student programming to the Cross Timbers region.
The Tallgrass Prairie Preserve, located in Osage County, Oklahoma near Foraker, Oklahoma, is owned and managed by The Nature Conservancy.
 It is protected as the largest tract of remaining tallgrass prairie in the world.
 The preserve contains 39000 acre owned by the Conservancy and another 6000 acre leased in what was the original tallgrass region of the Great Plains that stretched from Texas to Manitoba.
Nine Mile Prairie (named for its location 5 mi west and 4 mi north of downtown Lincoln) is a 230 acre tract of conserved tallgrass prairie in Lancaster County, Nebraska, United States.
 Except for one small portion of it that was farmed as recently as the 1950s, Nine-Mile Prairie has never been plowed (some of the land has at times been grazed as recently as the 1960s).
 As such, it is one of the largest areas of virgin tallgrass prairie in the state of Nebraska.
 It has been listed on the National Register of Historic Places since 1986.
The Osage Hills is a hilly area in Oklahoma, commonly known as "The Osage".
 The name refers to the broad rolling hills and rolling tallgrass prairie and Cross Timbers encompassing Osage County and surrounding areas, including portions of Mayes, Tulsa, Washington and Kay Counties.
 The Osage is the southern extension of the Flint Hills of Kansas.
The Midewin National Tallgrass Prairie (MNTP) is a tallgrass prairie reserve and United States National Grassland operated by the United States Forest Service.
 The first national tallgrass prairie ever designated in the U.S. and the largest conservation site in the Chicago Wilderness region, it is located on the site of the former Joliet Army Ammunition Plant between the towns of Elwood, Manhattan and Wilmington in northeastern Illinois.
Tallgrass Prairie National Preserve is a United States National Preserve located in the Flint Hills region of Kansas, north of Strong City.
 The preserve protects a nationally significant example of the once vast tallgrass prairie ecosystem.
 Of the 400,000 square miles (1,000,000 km) of tallgrass prairie that once covered the North American continent, less than 4% remains, primarily in the Flint Hills.
 Since 2009, the preserve has been home to the growing Tallgrass Prairie bison herd.
Osage County is the largest county by area in the state of Oklahoma in the United States.
 Created in 1907 when Oklahoma was admitted as a state, the county is named for and is home to the federally recognized Osage Nation.
 The county is coextensive with the Osage Nation Reservation, established by treaty in the 19th century when the Osage relocated there from Kansas.
 The county seat is in Pawhuska, Oklahoma, one of the first three towns established in the county.
 The total population of the county is 47,987.