This miniature watercolor on ivory portrait of William Thornton was created by Robert Field circa 1800. Dr. William Thornton was born in the British West Indies in 1759 and gained U.S. citizenship in 1787. Thornton moved to Washington, D.C. after President George Washington chose his design for the U.S. Capitol building and appointed him a city commissioner. Considered the "first architect of the Capitol," Thornton held the role of head of the Patent Office from 1802 until his death in 1828. William Thornton and the creator, Robert Field, were acquaintances. This portrait is a part of the White House Collection.

This painting is attributed to William Henry Powell (sometimes known as W.H. Powell), who was a New York City painter and trained under Henry Inman. The painting depicts a group of settlers and their horses around a covered wagon. An American Indian man is in the center of the group and pointing off into the distance, suggesting he is providing directions to the seated figure looking at a map. Powell's "Discovery of the Mississippi by De Soto A.D. 1541" hangs in the United States Capitol Rotunda.