County Mayo () (Irish: Maigh Eo, meaning “Plain of the yew trees”) is a county in Ireland. It is located in the West Region, and it is also part of the province of Connacht. It is named after the village of Mayo, which is now generally known as Mayo Abbey. Mayo County Council is the local authority for the county. The population of the county is 130,638 according to the 2011 census. The boundaries of the county, which was formed in 1585, reflect the Mac William Íochtar lordship at that time.