What was once the biggest secret in America is being commemorated in public—building the bomb. The National Park Service and the Department of Energy announced last week the establishment of three national historic parks at Manhattan Project sites. The three sites, in Oak Ridge, Tennessee; Los Alamos, New Mexico; and Hanford, Washington, will commemorate the places where work on the atomic bomb was completed during World War II.

Read about the Gettysburg Address or watch the lecture "The Eloquent President: A Portrait of Lincoln through His Words" by Professor Ronald C. White of the University of California, Los Angeles.

In October of 1901, President Theodore Roosevelt invited Booker T. Washington to dine at the White House. As the founder of the Tuskegee Institute and a respected leader of the African American community, Washington was an important ally for Roosevelt. The new president needed advice about appointments in the South and about the black vote, and looked to Washington for guidance.

Each summer, the Gilder Lehrman Institute offers academically rigorous seminars for K–12 educators and National Park Service interpreters. Held at colleges and historic sites across the US and abroad, the weeklong seminars offer teachers lectures and discussions with eminent historians, visits to historic sites, and hands-on work with primary sources. Room, board, and tuition are fully paid for public school teachers, and matching funds are available for independent school teachers.

In 1904, the US took over a massive overseas building project—a ship canal in Panama that would connect the Atlantic Ocean to the Pacific Ocean. This wasn’t a new idea.