Oscar De La Hoya vs. Félix Trinidad, billed as The Fight of the Millennium, was a boxing match held in Las Vegas, Nevada, on September 18, 1999, to unify the WBC and IBF's world Welterweight championships.
Oscar De La Hoya vs. Shane Mosley II, billed as "Redemption", was a professional boxing match contested on September 13, 2003 for De La Hoya's WBA, WBC, "The Ring" and lineal super welterweight (light–middleweight) championships.
Oscar De La Hoya vs. Fernando Vargas, billed as "Bad Blood", was a professional boxing match contested on September 14, 2002, for De La Hoya's WBC and lineal super welterweight (light–middleweight) championships, Vargas' WBA super welterweight championship, and the vacant "The Ring" light–middleweight championship.
Oscar De La Hoya vs. Julio César Chávez II, billed as "Ultimate Revenge", was a professional boxing match contested on September 18, 1998 for the WBC and lineal welterweight championships.
The Las Vegas Valley is a major metropolitan area located in the southern part of the U.S. state of Nevada.
 The largest urban agglomeration in the state, it is the heart of the Las Vegas–Paradise-Henderson, NV MSA.
 The Valley is largely defined by the Las Vegas Valley landform, a 600 sqmi basin area surrounded by mountains to the north, south, east and west of the metropolitan area.
 The Valley is home to the three largest incorporated cities in Nevada: Las Vegas, Henderson and North Las Vegas.
 Five unincorporated towns governed by the Clark County government are part of the Las Vegas Township and constitute the largest community in the state of Nevada.
Oscar De La Hoya vs. Shane Mosley, billed as "Destiny", was a professional boxing match contested on June 17, 2000 for the WBC, IBA (both held by De La Hoya) and the vacant lineal welterweight championships.
Oscar De La Hoya vs. Rafael Ruelas, billed as "La Batalla", was a professional boxing match contested on May 6, 1995 for the WBO and IBF lightweight championships.
 The fight is notable for being the first pay-per-view headlined by De La Hoya, who would eventually go on to become the biggest draw in boxing pay-per-view history.
Bernard Hopkins vs. Oscar De La Hoya, billed as "History", was a professional boxing match contested on September 18, 2004 for Hopkins' WBA, WBC, IBF, "The Ring" and lineal middleweight championships, and De La Hoya's WBO middleweight championship.
De La Hoya vs. Mayweather: The World Awaits was a super welterweight superfight that took place on May 5, 2007, at the MGM Grand Arena in Las Vegas, Nevada between six-division world champion Oscar De La Hoya (38–4, 30 KO) and undefeated four-division champion Floyd Mayweather Jr. (37–0, 24 KO).
 At the time, the bout was the most lucrative boxing match ever, with over $130 million in generated revenue.
Oscar De La Hoya vs. Manny Pacquiao, also billed as The Dream Match, was a professional boxing welterweight superfight.
 The bout took place on December 6, 2008 at the MGM Grand Garden Arena, Las Vegas, Nevada, United States.
 Pacquiao defeated De La Hoya via technical knockout when De La Hoya decided not to continue with the fight before the start of the ninth round.
 The card was a co-production of Bob Arum's Top Rank Boxing and De La Hoya's Golden Boy Promotions and was aired live on pay-per-view (PPV) on HBO PPV.
 The fight is notable for propelling Manny Pacquiao to full-blown superstar status in much of the western world (mostly in The United States), as Oscar De La Hoya symbolically "passed the torch", so to speak, to Pacquiao.

Question: Oscar De La Hoya vs. Félix Trinidad was a boxing match held in which urban agglomeration in Nevada?
Answer: Las Vegas Valley