1. On July 10, 1890, South Dakota became the 40th state to join the Union. The decision was made after the Dakota Territory was split into two separate states, North and South Dakota.

2. In 1921, Deadwood, a town in the Black Hills region of South Dakota, was hit by a massive flood on July 10. The flood destroyed many buildings and caused extensive damage. It also led to the construction of a new bridge, the Chautauqua Footbridge, which still stands today as a historic landmark.

3. July 10, 1945, marks the day when the South Dakota Army National Guard's 109th Engineer Combat Battalion landed on Omaha Beach in Normandy, France, during World War II. The battalion played a vital role in the Allied victory by constructing and maintaining bridges and roads to support the troops' advance towards Germany.

4. On July 10, 1981, the historic Corn Palace in Mitchell, South Dakota, caught fire, causing extensive damage. The iconic building, which features murals made entirely from corn cobs, was rebuilt and remains a popular tourist attraction in the state.

5. July 10, 1998, is the day when South Dakota senator Larry Pressler introduced the Child Online Protection Act (COPA) in Congress. The act aimed to protect minors from harmful online content but faced legal challenges and was eventually struck down by the Supreme Court in 2004 as a violation of the First Amendment.