Question: When did the first Walmart open in the state where Ditto Knolls is located?

full_context: Document 1: J. Stinson Farm: J. Stinson Farm is a historic farm located near Newark, New Castle County, Delaware. The property includes three contributing buildings. They are a stone and frame bank barn (c. 1810), an early 19th-century stuccoed masonry house with an addition dated to about 1900, and a late-19th century, frame implement shed. The house is a two-story, three bay, gable-roofed, stuccoed stone building. It has a Georgian form and the addition has Queen Anne style detailing.
Document 2: Routzahn-Miller Farmstead: The Routzahn-Miller Farmstead is a historic home and farm complex located at Middletown, Frederick County, Maryland, United States. It consists of a Federal style-influenced brick house and smokehouse, both built about 1825; a later frame out-kitchen / washhouse; a standard Pennsylvania barn; a 20th-century dairy barn and milk house; and a 20th-century equipment shed. The Pennsylvania barn was probably built in the late 19th century and was recently rehabilitated for use as a preschool. The complex is located on a parcel on the east flank of South Mountain. It is representative example of a type of domestic and agricultural grouping which characterized the rural mid-Maryland region from the early 19th century through World War II era.
Document 3: History of Walmart: In April 1983, the company opened its first Sam's Club store, a membership - based discount warehouse club, in Midwest City, Oklahoma. They also expanded into Indiana, Iowa, New Mexico, and North Carolina and implemented ``people greeters ''in all of their stores. The first stores opened in Virginia in 1984.
Document 4: Jeptha Hayman House: The Jeptha Hayman House, also known as Hayman Farm, is a historic home located at Kingston, Somerset County, Maryland, United States. It is a two-story, five-bay weatherboard frame dwelling in the Greek Revival-style. The oldest portion is dated by an inscribed brick to 1836, with an addition about 1850. The house features a Tuscan-columned porch supported on a Rusticated concrete block knee wall.
Document 5: Sam's Club: As of January 31, 2018, Sam's Club operates 597 membership warehouse clubs in 44 U.S. states. Alaska, Massachusetts, Oregon, Rhode Island, Vermont, and Washington are the only states where Sam's Club does not operate, as is the case for the District of Columbia. Walmart International also operates Sam's Clubs in Mexico, Brazil, and China. It has 162 locations in Mexico, 27 locations in Brazil, and 19 in China. Locations generally range in size from 94,000 -- 161,000 sq ft (8,700 -- 15,000 m), with an average club size of approximately 134,000 sq ft (12,400 m).
Document 6: History of Walmart: By 1988, Walmart was operating in 27 states, having expanded into Arizona, Michigan, Ohio, West Virginia, New Jersey, and Wyoming. By 1990, they expanded into California (which marked Walmart officially becoming a fully nationwide retailer), Nevada, North Dakota, Pennsylvania, South Dakota, and Utah. The Walmart Visitor's Center also opened this year on the site of Sam Walton's original store.
Document 7: John Walter Farmstead: John Walter Farmstead, also known as Lengauer House, is a historic home located in Washington Township, Westmoreland County, Pennsylvania. The house was built in 1848, and is a two-story, "L"-shaped red brick dwelling, five bays wide in the Greek Revival style. It has a low-pitched, slate covered gable roof. The front facade has a three bay, hipped roof porch. Associated with the house is a contributing bank barn, built about 1846, and spring house, built in 1912.
Document 8: Ditto Knolls: Ditto Knolls is a historic home and farm located near Hagerstown, Washington County, Maryland, United States. It was built about 1790, and is a five-bay, two-story brick house with a two-bay, one-story brick rear wing. It features a one-story entrance porch supported by Doric columns. Also on the property is a large stone bank barn and springhouse. It is one of two historic farm complexes located in Ditto Farm Regional Park, along with the Henry McCauley Farm.
Document 9: Walmart: Walmart Inc. Walmart's current logo since 2008 Walmart's official headquarters in Bentonville, Arkansas Formerly called Wal - Mart, Inc. (1969 -- 70) Wal - Mart Stores, Inc. (1970 -- 2018) Type Public Traded as NYSE: WMT DJIA component S&P 100 component S&P 500 component ISIN US9311421039 Industry Retail Founded July 2, 1962; 55 years ago (1962 - 07 - 02) Rogers, Arkansas, U.S. Founder Sam Walton Headquarters Bentonville, Arkansas, United States Number of locations 11,718 stores worldwide (January 31, 2018) Area served Worldwide Key people Greg Penner (Chairman) Doug McMillon (President & CEO) Products Electronics Movies and music Home and furniture Home improvement Clothing Footwear Jewelry Toys Health and beauty Pet supplies Sporting goods and fitness Auto Photo finishing Craft supplies Party supplies Grocery Services Walmart - 2 - Walmart Walmart MoneyCard Pickup Today Walmart.com Walmart Pay Revenue US $500.34 billion (2018) Operating income US $20.437 billion (2018) Net income US $9.862 billion (2018) Total assets US $204.52 billion (2018) Total equity US $77.869 billion (2018) Owner Walton family (51%) Number of employees 2.3 million, Worldwide (2017) 1.4 million, U.S. (2017) Divisions Walmart U.S. Walmart International Sam's Club Global eCommerce Subsidiaries Walmart Canada Walmart Mexico Walmart Chile Walmart de México y Centroamérica @ WalmartLabs Walmart Neighborhood Market Asda Amigo Supermarkets Vudu Massmart Seiyu Group Bompreço Líder Jet.com Hayneedle Moosejaw ModCloth Flipkart Website Corporate website Commercial website Footnotes / references
Document 10: Ludwick Rudisel Tannery House: The Ludwick Rudisel Tannery House, also known as Motter Place, is a historic home located at Taneytown, Carroll County, Maryland, United States. The main block is constructed of brick on a fieldstone foundation, five bays in length, two deep, with an original slate roof, built about 1807. Attached is a two-story, two-bay-long brick kitchen. The house features Georgian massing and fine Federal detailing.
Document 11: Jacob Highbarger House: The Jacob Highbarger House was built "circa" 1832 in Sharpsburg, Maryland, United States. The Greek Revival-influenced house is a late example of limestone construction in the Cumberland Valley of Maryland, with an attached log workshop. The log structure is an unusual example of corner-post log construction with diagonal bracing.
Document 12: Providence Plantation and Farm: Providence Plantation and Farm, also known as Fogg House and Farm, is a historic plantation house located near Newtown, King and Queen County, Virginia. The main was built about 1826, and altered about 1840. It is a two-story, three bay, brick house with Federal style design influences. Also on the property are the contributing two-story Reconstruction-era granary and carriage house, and Great Depression-era hen laying house, two-story sweet potato shed, and mechanic's shop.
Document 13: History of Walmart: In 1981, Wal - Mart expanded into the southeastern US market, opening stores in Georgia and South Carolina, and acquiring 92 Kuhn's Big K stores. They expanded into Florida and Nebraska in 1982.
Document 14: History of Walmart: By 1977, Wal - Mart expanded into Illinois and made its first corporate acquisition, assuming ownership and operation of the Mohr - Value stores, which operated in Missouri and Illinois. This was followed by the acquisition of the Hutcheson Shoe Company in 1978. In the same year Walmart also branched out into several new markets, launching its pharmacy, auto service center, and jewelry divisions.
Document 15: History of Walmart: In 1991, the company expanded into Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, and New York. Walmart expanded worldwide this year, with the opening of their first store outside the United States in Mexico City. They also acquired Western Merchandisers, Inc. of Amarillo, Texas. 1991 also saw the launch of the Sam's American Choice brand of products.
ground_truth: 1991
sub_queries: What is the name of the state where Ditto Knolls is located? Answer: Maryland
when did the first walmart open in Maryland Answer: 1991