The city's population, which had reached one million in the early 1960s, also expanded rapidly after 1967, exceeding two million by the mid-1970s. Although growth within the city itself gradually slowed thereafter — its population had become relatively stable by the mid-1990s – Taipei remained one of the world's most densely populated urban areas, and the population continued to increase in the region surrounding the city, notably along the corridor between Taipei and Keelung.