In George Mifflin Dallas, Thomas Sully presents a formal portrait of the American politician. The painting features a dignified figure dressed in a dark coat, with a white shirt and cravat, set against a muted background. Sully uses rich, warm colors that enhance the subject's presence and authority.

The lighting is soft, highlighting the face and creating a sense of depth. The painting is executed in oil on canvas, a medium that allows for detailed textures and vibrant colors. Sully's technique includes smooth brushwork that captures the likeness of Dallas effectively. The dimensions of the artwork are approximately 76 x 102 cm, making it a substantial portrait.

The composition is balanced, with Dallas positioned centrally, drawing the viewer's attention. Thomas Sully was a prominent American painter known for his portraits and historical scenes. This work, created in the 1840s, reflects the Romantic style that was prevalent during that period. An interesting fact about this painting is that George Mifflin Dallas served as the 11th Vice President of the United States, and Sully's portrayal contributes to the historical narrative of American political figures.

The painting remains a significant representation of 19th-century American portraiture.