1. Nebraska's First Post Office Established: On June 17, 1856, the first post office in Nebraska was established in the city of Omaha. The post office was initially located on the second floor of a local store, and Jacob S. Shankland was appointed as the first postmaster.

2. Nebraska Joins the Union: Nebraska officially became the 37th state of the United States on June 17, 1867. The state was admitted to the Union during the Reconstruction era, following the American Civil War.

3. The Great Flood of 1881: On June 17, 1881, heavy rainfalls resulted in one of the worst floods in Nebraska's history. The flooding caused widespread damage and destruction in several cities, and it is estimated that more than 100 lives were lost as a result of the disaster.

4. The Birth of Willa Cather: Willa Cather, one of Nebraska's most celebrated writers, was born on June 17, 1873, in Virginia. She moved to Nebraska at the age of nine and spent most of her adult life in the state. Cather's most famous works, including "My Ántonia" and "O Pioneers!", are set in Nebraska.

5. Nebraska's First Native American Legislator Elected: On June 17, 1972, Frank LaMere was elected as Nebraska's first Native American legislator. LaMere, a member of the Winnebago Tribe, served in the Nebraska Legislature from 1973 to 1977 and later became a prominent activist and advocate for Native American rights.