Question: What year did construction of Six Flags Over Texas start?
About the article "Six Flags", section "Beginnings".

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Six Flags Over Texas is a 212-acre (86 ha) theme park located in Arlington, Texas, east of Fort Worth and about 15 miles (24 km) west of Dallas.
It was the first Six Flags Theme Park, but because of later acquisitions it is not the oldest park of the Six Flags chain.
The park opened on August 5, 1961, following just a year of construction and an initial investment of US$10 million by real estate developer Angus G. Wynne, Jr.
Since its opening, Six Flags Over Texas has consistently performed well in terms of attendance and revenue, despite its history of ever-changing owners and expansions.
The park currently has several amusement rides and attractions, bringing in thousands of visitors daily.
The park is managed, but not owned, by the Six Flags corporation, in an arrangement similar to that for Six Flags Over Georgia.
Six Flags Over Texas is owned by a group of approximately 120 limited partners—some the heirs of Angus G. Wynne.
Starting in 1991, the park was managed by Time Warner Entertainment.
In 1998, Time Warner sold its interests in the Six Flags parks to Premier Parks of Oklahoma City, which later changed its name to Six Flags Theme Parks, Inc. 
Six Flags Hurricane Harbor, Arlington is located near Six Flags Over Texas.
It was originally a part of the Wet 'n Wild chain, but was purchased by Six Flags in 1995. 
 Design, construction and trains  "Outlaw Run" at Silver Dollar City - wooden roller coaster  "Goliath" at Six Flags Great America - wooden roller coaster I-Box retrack  "Iron Rattler" at Six Flags Fiesta Texas  "Texas Giant" at Six Flags Over Texas  "Medusa Steel Coaster" at Six Flags México Topper Track  "Cyclone" at Six Flags New England  "Georgia Cyclone" at Six Flags Over Georgia   "Medusa" at Six Flags México  "The Rattler" at Six Flags Fiesta Texas  "Tremors" at Silverwood Theme Park  "Le Monstre" at La Ronde Construction  "Aftershock" at Silverwood Theme Park  "El Toro" at Six Flags Great Adventure  "T Express" at Everland  "Timber Terror" at Silverwood Theme Park  "Tremors" at Silverwood Theme Park  "Villain" at Six Flags Worlds of Adventure  "Timberhawk" at Wild Waves Theme Park Repairs  "The Boss at Six Flags St. Louis  "Cornball Express" at Indiana Beach  "Hoosier Hurricane" at Indiana Beach  "" at Myrtle Beach Pavilion  "Mega Zeph" at Six Flags New Orleans  "Predator" at Darien Lake  "Psyclone" at Six Flags Magic Mountain  "Thunder Run" at Kentucky Kingdom  "Timber Terror" at Silverwood Theme Park  "Tremors" at Silverwood Theme Park  "Twister II" at Elitch Gardens Theme Park  
  Flashback (Six Flags Magic Mountain), steel roller coaster located at Six Flags Magic Mountain, USA  Flashback (Six Flags New England), steel roller coaster of shuttle design currently in use at Six Flags New England, USA  Flashback (Six Flags Over Texas), a steel boomerang roller coaster located at Six Flags Over Texas in Arlington, Texas, USA  
 , roller coaster at Six Flags Magic Mountain.
, roller coaster at Six Flags Over Georgia, Six Flags Great Adventure, and Six Flags Great America.
, roller coaster at Six Flags Discovery Kingdom Superman – Ride of Steel, roller coaster at Six Flags America.
, roller coaster at Six Flags Fiesta Texas.
Superman el Último Escape, roller coaster at Six Flags México.
Superman la Atracción de Acero, roller coaster at Parque Warner Madrid Superman Escape, roller coaster at Warner Bros. Movie World.
tower ride at Six Flags Over Texas and Six Flags St. Louis.