In a letter to Montgomery Meigs, Thomas Crawford explained the symbolism of the Pediment's center:

The central figure of the composition represents America standing upon a rock against which the waves of the ocean are beating. She is attended by the Eagle of our country, while the sun rising at her feet indicates the light accompanying the march of liberty. In one hand she holds the rewards of civic and military merit--the laurel and the oak wreath. The left hand is held out towards the pioneers for whom she asks the protection of the Almighty.