How did Lincoln-Douglas debates benefit Abraham Lincoln?

Until the 17th Constitutional Amendment of 1913, senators were elected by state legislatures, so Lincoln and Douglas were trying to win control of the Illinois General Assembly for their respective parties. The debates previewed the issues that Lincoln later faced after his victory in the 1860 presidential election.

(Oil) In the early 20th century the members of the osage nation became the richest people per capita in the world, after oil was discovered under the reservation in Northwest Oklahoma. Answer- Oil.