1. The Mountain Meadows Massacre occurred on May 18, 1857: This was a tragic event in Utah's history where a group of Mormon settlers and Native American allies attacked an emigrant wagon train and killed over 120 men, women, and children.

2. The Transcontinental Railroad was completed in Utah on May 10, 1869: Although it wasn't on May 18th specifically, this event had a huge impact on Utah's history. The railroad connected the east and west coasts of the United States and made travel and transportation of goods much easier.

3. The first women were allowed to vote in Utah on May 18, 1870: Utah was the first state to grant women the right to vote after Wyoming, which was a territory at the time. This was a significant moment in the fight for women's suffrage.

4. The first electric power plant in Utah was turned on May 18, 1881: This power plant was located in Salt Lake City and provided electricity to street lamps, homes, and businesses.

5. The University of Utah moved to its current campus on May 18, 1900: The University of Utah was originally located in downtown Salt Lake City but was moved to its current location in the foothills of the Wasatch Mountains in 1900. The campus has since grown into a large and prestigious university.