Until Barack Obama visited the Keystone Pipeline on March 22, 2012, and stayed over in the capital, no sitting US president had spent the night in Oklahoma since 1992 - before the Oklahoma City attack that killed 168 people and wounded 700 others.
The bomb blast, considered an act of domestic terrorism, was the worst single instance of any type of terrorism in the US until the September 11, 2001, attacks.
The dead mostly included employees of the federal government who had just arrived in their offices for the start of the work day, as well as 19 children who were at a day-care centre on the building's second floor. The widespread destruction masterminded by Timothy McVeigh and Terry Nicholes, in addition to the response by emergency teams across the region and beyond, became the main event in America's national consciousness associated with Oklahoma City.
The site's outdoor memorial was dedicated by President Bill Clinton in 2000, and then President George W Bush attended the museum dedication in 2001. Expansion of the current building has entered the planning stages, in advance of 20th anniversary ceremonies for 2015.
Al Jazeera spoke with some visitors about the memorial's symbolism, recollections from 17 years ago and the 2012 presidential election.