The Northwest Mosquito Abatement District was formed on December 28, 1959 to control mosquitoes in the northwest portion of Riverside County encompassing 150 square miles. The population of the District at that time was approximately 50,000 residents. Since inception, the District has grown significantly in population and area. Additionally, the geographical landscape has changed dramatically, from rural to mostly urban and suburban, thus creating a different set of vector problems. In 1968, upon request by the Board of Supervisors, the Board of Trustees adopted the additional responsibility of controlling biting gnats in areas adjacent to the Santa Ana River without additional revenues to the District. On August 16, 1993, the District added services to control all important vectors and changed its name to NORTHWEST MOSQUITO AND VECTOR CONTROL DISTRICT. In July 1994, the District purchased its present facility and relocated its headquarters to Corona. At present, the District provides vector control services (mosquito, flies, rats, Africanized honeybees, black flies, midges and occasionally other vectors of minor public health importance) over an area of 350 square miles with a population of approximately 850,000.