On this day in 1846, Mexican and American forces clash in a disputed area close to the Rio Grande. The so-called Thornton Affair would...

On this day in 1861, the first transcontinental telegraph is sent, bringing an end to the Pony Express. The task seemed impossible at...

On this day in 1803, the United States Senate approves the Louisiana Purchase. Americans had just purchased an 827,000 square mile block...

On this day in 1898, an American flag is raised over Puerto Rico. The island was no longer a Spanish possession. It was under the control...

On this day in 1846, the United States declares war on Mexico. President James Polk had asked Congress for such a declaration a mere two...

On this day in 1769, Daniel Boone gets his first good look at the territory in Kentucky—or “Kentucke,” as it was sometimes called. The...

On this day in 1867, the United States takes control of territory in Alaska. Secretary of State William Seward had just brokered a deal...