The Idaho state flag was adopted on March 12, 1907. The 13-cent Idaho State Flag stamp (Scott 1675) features the state seal on a field of blue. A red banner bordered in gold is directly under the seal, and on the banner are the words "State of Idaho."
The woman on the state seal signifies justice, as noted by the scales; liberty, as denoted by the liberty cap on the end of the spear; and equality with man as denoted by her position at his side. The pick and shovel held by the miner, the ledge of rock beside which he stands, and the ore scattered about the feet indicate the state’s chief occupation.
The shield between the man and woman represents the protection together they give the state. The large fir or pine tree in the foreground of the shield refers to Idaho's timber interests. The husbandman plowing on the left side of the shield and the sheaf of grain beneath the shield represent agricultural resources, while the cornucopias, or horns of plenty, refer to horticulture. The elk's head rises above the shield; the state flower, the wild Syringa or Mock Orange, grows at the woman's feet, while the ripened wheat grows as high as her shoulder. The star signifies a new light in the galaxy of states, and the river depicted is the Snake or Shoshone River.
Scott 2005 Specialized Catalogue of U.S. Stamps and Covers
SHG Resources (http://www.shgresources.com/id/symbols/flag/)