Primary or Secondary Sources?

Emigrant Ad and Pony Express Album

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"Ho for Kansas!" advertisement
This is an advertisement for the Real Estate and Homestead Association located in Nashville, Tennessee announcing their departure for Kansas on 15 April, 1878. The ad encourages people to contact Benjamin Singleton for more information "in the pursuit of southwestern lands in the Americas" and the transportation to get to Kansas. This ad not only promotes the selling and buying of land in the American West, but part of a movement to encourage African Americans to move to the trans-Mississippi west after the Civil War.
Courtesy of Library of Congress.
Date: March 18, 1878

One of these objects is a primary source for the 1800s. Which one is it, and how do you know? Give reasons for your conclusion.

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"The Pony Express" record album
Record Album produced by CRG (Children's Record Guild), a Ddivision of the American Recording Society in New York. The story of the Pony Express is told by John Griggs through dramatic narrative and interpretations; the recording also includes three songs performed by the Gene Lowell Chorus. The three songs highlight Buffalo Bill, Wild Bill Hickok, and Pony Bob Haslam as Pony Express riders. Of the three, only Pony Bob Haslam has been confirmed as an official Pony Express rider through historical documents.
Date: 1951