The Grapes of Wrath
One of the great American realist novels and a top empathy book. Set during the Great Depression, the novel focuses on the Joads, a poor family of tenant farmers driven from their Oklahoma home by drought, economic hardship, and changes in the agricultural industry forcing tenant farmers out of work. Due to their nearly hopeless situation, and in part because they were trapped in the Dust Bowl, the Joads set out for California. Along with thousands of other "Okies", they sought jobs, land, dignity, and a future.
In terms of empathy, the story of the Joads offers insights into the human realities of the Depression the 1930s, and the daily struggles of families attempting to escape its ravages. It’s definitely of the best novels I know of to convey the experiences of poverty.