Question: Where is the preserve that Patricia DuBose Duncan supported for designating as some of the last tall grass prairie land?

Context paragraphs:
In the Tall Grass: In the Tall Grass is a novella written by Stephen King and his son Joe Hill.  It was originally published in two parts in the June/July and August 2012 issues of "Esquire" magazine.  This is King and Hill's second collaboration since "Throttle", published in 2009.  On October 9, 2012, "In the Tall Grass" was released in e-book and audiobook formats, the latter read by Stephen Lang.

Andropogon gerardi: Andropogon gerardi, known commonly as big bluestem, turkeyfoot, tall bluestem, and bluejoint, is a tall grass (family Poaceae) native to much of the Great Plains and prairie regions of central North America and grasslands, savannas and woodlands throughout eastern North America.

Tallgrass Prairie National Preserve: 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.

Prairie Learning Centre: The Prairie Learning Centre (PLC) is an educational centre located near Grasslands National Park, Saskatchewan, that hosts curriculum linked workshops on the native prairie landscape.  With the support of Grasslands National Park, Chinook School Division and the Village of Val Marie, Saskatchewan, the Prairie Learning Centre provides innovative learning opportunities for secondary school students.  The PLC aims to promote stewardship of the mixed grass prairie ecosystem.

Patricia DuBose Duncan: Patricia DuBose Duncan (born 1932) is an artist living in Topsham, Maine.  She is best known for her work to gain support for designating some of the last remaining tall grass prairie land in the American Midwest, as the Tallgrass Prairie National Preserve.  This land was publicized in a Smithsonian Traveling Exhibition (S.I.T.E.S.) in 1976-86 as a Bicentennial Exhibition.  The exhibit has been digitally preserved by Kansas State University's Marianna Kistler Beach Museum of Art.

Prairie restoration: Prairie restoration is an ecologically friendly way to restore some of the prairie land that was lost to industry, farming and commerce.  For example, the U.S. state of Illinois alone once held over 35,000 sqmi of prairie land and now just 3 sqmi of "original" prairie land exist.

Little Missouri National Grassland: Little Missouri National Grassland is a National Grassland located in western North Dakota, USA.  At 1028051 acres , it is the largest grassland in the country.  Enclaved within its borders is Theodore Roosevelt National Park, which is managed by the National Park Service (and therefore not included in the preceding statistics).  The Little Missouri National Grassland was once a part of the Custer National Forest, but is now a part of the Dakota Prairie Grasslands, a National Forest unit consisting entirely of National Grasslands.  A predominant feature of the grassland is colorful and beautiful badlands, a rugged terrain extensively eroded by wind and water.  It is a mixed grass prairie, meaning it has both long and short grass.

Osage State Fishing Lake: Osage State Fishing Lake is located in northern Osage County, Kansas.  It is a mile east of US 75.  Scranton, Kansas, is to the lake's northwest and Overbrook, Kansas, is to the northeast.  Osage Lake is a freshwater man-made lake, constructed in 1955.  It has a surface area of 140 acres, The parkland in which the lake is contained has 366 acreas of land, mostly tall grass prairie with numerous wooded areas.  The lake is owned by the State of Kansas.

Manitoba Tall Grass Prairie Preserve: The Manitoba Tall Grass Prairie Preserve is located in southeastern Manitoba near Gardenton and Vita, this is about 50 km south of Steinbach, Manitoba.  It is one of the last remaining stands of tallgrass prairie in Manitoba and is part of the Tallgrass Aspen Parkland conservation area in Manitoba and Minnesota.  Several groups and organizations help in land preservation in the Manitoba Tall Grass Prairie such as the Nature Conservancy of Canada, Nature Manitoba, Environment Canada, Manitoba Conservation and the Manitoba Habitat Heritage Corporation.

Living Prairie Museum: The Living Prairie Museum is a 12 hectare (30 acre) tall grass prairie preserve located in Winnipeg, Manitoba.  It was discovered in 1968 when a local sub-committee of the International Biological Program surveyed Manitoba for native prairie plant communities.  Of more than 60 sites that were researched, only four were found uncultivated.  Ironically, one of the largest undisturbed sites was discovered in a residential area of Winnipeg.  Today a vestige of this original prairie community has been set aside as a City of Winnipeg Nature Park, called the Living Prairie Museum (LPM).

Supporting paragraphs: Patricia DuBose Duncan Tallgrass Prairie National Preserve
Answer: Flint Hills region of Kansas, north of Strong City