Silao (), officially Silao de la Victoria, is a city in the west-central part of the state of Guanajuato in Mexico. It is the seat of the municipality with the same name. As of the 2005 census, the city had a population of 147,123, making it the seventh-largest community in the state. Silao is a center of agricultural and industrial activity. Airport This city is served by the Del Bajío International Airport. It functions as the central airport for the cities of Irapuato, Guanajuato, León, Salamanca and San Miguel de Allende. Toponymy In its original Otomi language, the area was called Tsinäkua by both the Otomi and Purépecha natives. In the Otomi language its name Tsinäkua means 'place of dense fog,' as a result of the columns of water vapor rising from thermal springs in the area of Comanjilla. The name evolved to 'Sinaua', 'Silagua' and finally 'Silao' after the Spanish conquest of the region. History In the place where Silao now sits, there was an Otomí settlement that was conquered by the Purépecha empire. The name of the area remained Tsinäkua under Purepecha rule. The name evolved to 'Sinaua', 'Silagua' and finally 'Silao' after the region was later conquered by Spain. Geography Silao is located in the Mexican state of Guanajuato. It is situated 100° 25´ 59´´ longitude west of the Greenwich meridian and 20° 56' 24 latitude north. Its altitude is 1,780 meters above sea level. The municipality of Silao has an area of 531.41 km², equivalent to 1.76% of the total state area. The city of Guanajuato lies to the east and north of Silao; to the south lies Irapuato; to the west is Romita; to the northwest is León. Geology The territory of Silao is almost planar formed in by the Bajío, between its few important elevations, one can find the 'Cerro del Cubilete' whose altitude is 2,570 meters above sea level and is considered the geographic center of the country. Hydrography The Silao River, crosses the major part of the municipal territory. It is fed by the Magueyes, Pascuales, Hondo, and Tigre streams, as well as the Gigante River, which is its major tributary. Within the municipality are some streams of importance, like those of the Agua Zarca, San Francisco, El Paraíso, Pabileros, and Aguas Buenas. Climate The climate of the city is semi-arid in the majority of the territory, with rains in the summer