The economic situation of the colony declined following the Cariboo Gold Rush of 1861–1862, and pressure grew for amalgamation of the colony with the mainland colony of British Columbia (which had been established in 1858). The two colonies were merged in 1866 into the United Colonies of Vancouver Island and British Columbia by the Act for the Union of the colonies, passed by the Imperial Parliament. Arthur Kennedy was appointed governor of the united entity. (He would leave office in 1866 and later became Governor of the West African Settlements, British West Africa.) Victoria became the capital but the legislative assembly was located in New Westminster on the Lower Mainland. The capital was moved to Victoria in 1868.