Race
This period witnessed backsliding from the important progress of Reconstruction. Southern states circumvented the 15th Amendment, while courts proclaimed segregation to be consistent with equal protection. The first link describes what this meant for daily life. If you're looking for a happier topic, the second link describes how W. E. B. DuBois founded the NAACP. Another possible topic would be the way race featured in American imperialism. A second article explores the Filipino context for Rudyard Kipling's famous poem, "The White Man's Burden".
http://www.ferris.edu/jimcrow/what.htm
https://www.neh.gov/news/web-du-bois-and-the-foundation-the-naacp
https://monthlyreview.org/2003/11/01/kipling-the-white-mans-burden-and-u-s-imperialism/
Immigration
This was the classic period of immigration, in which newcomers transited Ellis Island under the gaze of the Statue of Liberty. You can find an overview by clicking the first link. A second one discusses the origin (and accuracy) of the melting pot analogy, whereby American culture subsumed that of successive immigrant waves.
http://www.ushistory.org/us/38c.asp
http://wilsonquarterly.com/stories/the-rise-and-fall-of-the-american-melting-pot/
Exceptionalism
America's openness to immigrants has always been part of arguments for exceptionalism. The link below quotes observers from our period to make that point
http://articles.sun-sentinel.com/2013-10-22/florida-jewish-journal/fl-jjps-fein-1023-20131022_1_american-exceptionalism-consent-president-obama
The American Dream
What did Americans strive for? One possible answer lies in their reading. Author Horatio Alger became a publishing sensation with a series of books in which poor protagonists achieve success through a combination of talent and hard work. The first link explores his relevance to the American Dream. Another clue to American aspiration lies in advertising, which attempted to tap the hopes and dreams of the public. Our second article describes the growth of advertising, both the practice and the profession.
https://letterpile.com/books/horatio-alger
https://www.boundless.com/u-s-history/textbooks/boundless-u-s-history-textbook/the-gilded-age-1870-1900-20/culture-in-the-gilded-age-157/mass-marketing-advertising-and-consumer-culture-781-9589/
Democracy
Progressives were passionate about democracy. One of their reforms was the 17th amendment, which allowed for the direct election of U. S. senators. The first link gives you a brief history. Another milestone was women's suffrage, which is discussed by the second article.
https://www.senate.gov/artandhistory/history/common/briefing/Direct_Election_Senators.htm
https://www.nwhm.org/online-exhibits/progressiveera/suffrage.html
Freedom
Early Republicans promoted "free labor", which they imagined in terms of ownership (of a farm or business). By the Gilded Age, this had evolved into "freedom of contract", the sale of labor to employers such as factories. This meant a decline in workers' independence, as described in our first link. Freedoms came into conflict again during World War I. Fighting a war for freedom of the seas and self-determination, we simultaneously suspended civil liberties at home. Americans went to jail for speaking against the war, as detailed in the second link.
https://www.thenation.com/article/shedding-lincolns-mantle/
http://ic.galegroup.com/ic/suic/ReferenceDetailsPage/ReferenceDetailsWindow?zid=8a0c202cd29a8bed89d3c53434a1aef3&action=2&catId=&documentId=GALE%7CEJ2104241252&userGroupName=clea26856&jsid=9264cced9a8f497a0e0debd85b7c3113
