The second map included in Washington Irving’s book: The Rocky Mountains; or Scenes, Incidents, and Adventures in the Far West. Later this was called The Adventures of Captain Bonneville. This book together with this map produced by Capt. Bonneville was a result of his expedition, was published in 1837
Counties existing in Deseret at the end of 1850 are blacked in on the map. The first counties were restricted to inhabited valleys. Iron County between January and December 1850 was called Little Salt Lake County. Davis County was created in October, 1850, out of Weber and Great Salt Lake Counties; the latter originally extended almost to the northern Davis County boundary.
An account of the shortest route to California illustrated by a history of explorations of the Great Basin of Utah with its topographical and geological character and some account of the Indian tribes
PDF can be found here.