1. In 1799, George Washington's tomb was completed at Mount Vernon, which became his final resting place. Washington had passed away the year before on December 14, 1799.

2. The U.S. Capitol building was completed on December 15, 1800. Started in 1793, the construction of the Capitol was delayed due to lack of funds and the War of 1812, but it ultimately became the iconic home of the United States Congress.

3. On December 15, 1845, the Oregon Treaty was signed between the United States and Great Britain, which settled a long-disputed border between the two countries. The treaty established the 49th parallel as the boundary between Canada and the United States, and also gave the US control of present-day Oregon, Washington, Idaho, and parts of Montana and Wyoming.

4. The Washington State Patrol was formed on December 15, 1921. Initially, the patrol consisted of just six officers who were tasked with enforcing traffic laws and ensuring public safety on the state's highways. Today, the patrol has more than 2,300 employees and is responsible for investigations and law enforcement throughout Washington State.

5. In 1993, former governor and US Senator Daniel J. Evans was appointed to the National Park System Advisory Board by President Bill Clinton. In this role, Evans provided advice and guidance on issues facing the National Park Service, including conservation, preservation, and showcasing the nation's natural and cultural resources.