A new mining rush and fourth building boom for Yellowknife began with the discovery of diamonds north of the city in 1991. The last of the gold mines in Yellowknife closed in 2004. Today, Yellowknife is primarily a government town and a service centre for the diamond mines. On 1 April 1999, its purview as capital of the NWT was reduced when the territory of Nunavut was split from the NWT. As a result, jurisdiction for that region of Canada was transferred to the new capital city of Iqaluit. Consequently, Yellowknife lost its standing as the Canadian capital city with the smallest population.