The Panic of 1893 was major depression of the American economy which lasted for four years and served as a major source of political upheaval. It is attributed partially to the failure of wheat crops in 1890, as well as a coup in Buenos Aires that ended investments via Baring Brothers, an Argentine agent bank. The issues cropping up in Argentina motivated European investors to cash in their investments for gold. With the crash of international commodity prices--which largely bolstered economic growth in the United States--so too came the crash of the American economy.
This issue first started popping up a mere two weeks before Grover Cleveland took office, when receivers were appointed to the already stretched-thin Reading Railroad and Philadelphia Railroad. As Cleveland scrambled to deal with the crisis in the Treasury, people panicked and withdrew their money from banks, ending in a huge credit issue. The panic worsened with the dawn of the Sherman Silver Purchase Act of 1890 and the McKinley Tariff.
This launched a depression in which banks, farms, and businesses collapsed and unemployment and poverty rates skyrocketed. Public opinion viciously blamed Cleveland and the Democratic party for the downturn, resulting in the largest Republic gains in the following election of 1894, during which Democrats and Populists failed miserably.
So what does any of this have to do with the book itself? The Devil in the White City focuses on the years surrounding the construction of The World's Columbian Exposition (otherwise known as the Chicago World's Fair of 1893), exploring the lives of Daniel Turnham (the architect responsible for the construction of the fair) and H.H. Holmes (a serial killer who prowls the fair).
The fair cost over $600 million to construct and was torn down after its completion (which lasted only eight months); this impermanent project was occurring on the heels of the aforementioned crisis, and the fact that it enabled the already wealthy and elite without providing any real benefits to the many people suffering throughout the country seemed like a deliberate slap in the face to those most affected by the panic. The book itself examines how the fair was allegedly used as a beacon in Chicago to light the way through "the gathering dark of economic calamity" while also detailing the very real ways in which people's lives were impacted by this glib and questionable creation.