The progress and developments of the prototypes influenced both the politics and the economics of the era leading eventually to the dual nationality of the aircraft, complex construction processes and massive overspends in the race for civil aviation supremacy. As Concorde prepared to enter service, her great potential for dominating the skies was being challenged by the new large aircraft being built by the Americans. Concorde would be much faster, but the US aircraft were cheaper to operate. Other aircraft could not come close to matching her swiftness, and elegance. Still, breaking into the all important American market would prove difficult. As Concorde evolved, so did the market challenges.