Michigan’s Great Seal was designed by Lewis Cass, Michigan’s second (non-acting) Territorial governor. The seal was patterned after the seal of the Hudson Bay Fur Company. It was presented to the Constitutional Convention of 1835 and adopted on June 2, 1835 as the official Great Seal of Michigan.
At the top of the Seal are the words, “E Pluribus Unum.” These words come from our national motto meaning, “From many, one.” Or, in other words, forming one nation from many states.
Below is the American Eagle, our national bird. This symbolizes the superior authority and jurisdiction or control of the United States. In its claws the eagle holds three arrows and an olive branch with 13 olives. The arrows show that our nation is ready to defend its principles. The olive branch means we want peace. The olives stand for the first 13 states.
“Tuebor,” meaning, “I will defend,” refers to Michigan’s frontier position.
The shield is held by two animals representing Michigan, the elk on the left and the moose on the right. Michigan is on an international boundary, and the figure of the man shows his right hand raised in peace. The left hand holds a gun to say that although we love peace, we are ready to defend our state and nation.
“Si Quaeris Peninsulam Amoenam Circumspice” means, “If you seek a pleasant peninsula, look about you.” It is believed this refers to the Lower Peninsula. The Upper Peninsula was added in 1837, to pay for the loss of a strip of land on our southern border, given to Ohio when Congress made Michigan a state.
The words, “The Great Seal of the State of Michigan, A.D. MDCCCXXXV,” complete the State Seal. When you take away these words and border, this becomes the Coat of Arms of the State of Michigan.
Changes in the Great Seal have been made from time to time. However, the present Seal has not been changed since 1911.
Source : History of the Great Seal, Michigan Secretary of State’s Office