41 Harriet Beecher Stowe

Her Uncle Tom’s Cabin inspired a generation of abolitionists and set the stage for civil war.

42 Eleanor Roosevelt

She used the first lady’s office and the mass media to become “first lady of the world.”

43 W. E. B. DuBois

One of America’s great intellectuals, he made the “problem of the color line” his life’s work.

44 Lyndon Baines Johnson

His brilliance gave us civil-rights laws; his stubbornness gave us Vietnam.

45 Samuel F. B. Morse

Before the Internet, there was Morse code.

46 William Lloyd Garrison

Through his newspaper, The Liberator, he became the voice of abolition.

47 Frederick Douglass

After escaping from slavery, he pricked the nation’s conscience with an eloquent accounting of its crimes.

48 Robert Oppenheimer

The father of the atomic bomb and the regretful midwife of the nuclear era.

49 Frederick Law Olmsted

The genius behind New York’s Central Park, he inspired the greening of America’s cities.

50 James K. Polk

This one-term president’s Mexican War landgrab gave us California, Texas, and the Southwest.

51 Margaret Sanger