The organizing committee celebrated Monday's milestone with an event at Pyeongchang's ski jumping centre and Olympic stadium site.
Kim Jong, an official with South Korea's sports ministry, said officials are "at a critical point" in preparations for the games, which will run from Feb. 9-25, 2018.
The South Korean government recently rejected a proposal by the International Olympic Committee to halt construction on a new bobsled, luge and skeleton venue and relocate the events to an existing sliding centre in another country. The IOC said the move would have saved $120 million in construction costs and $3.5 million in yearly maintenance fees.
The government also ruled out sharing events with rival North Korea.