1. On December 18, 1890, the first bridge across the Green River was completed. The bridge provided a vital connection between what are now the states of Colorado and Utah, facilitating transportation and commerce in the region.

2. December 18, 1926, marked the opening of the first electric traffic signal in Salt Lake City. The signal was installed at the intersection of Main Street and 200 South, and its success led to the widespread adoption of traffic lights throughout the state and beyond.

3. In 1944, December 18 was the day when the American Fork Canyon landslide occurred. The slide came down from the mountainside, causing extensive damage to roads, structures, and power lines in the area. Luckily, no one was killed or seriously injured in the event.

4. On December 18, 2002, Utah hosted the opening ceremonies of the 2002 Winter Olympics in Salt Lake City. The event brought millions of visitors and worldwide attention to the state, as athletes from around the world gathered to compete in a variety of winter sports.

5. December 18, 2013, saw the opening of City Creek Center, a massive mixed-use development in downtown Salt Lake City. The project included more than 100 stores and restaurants, as well as a new public park and pedestrian walkways. The development was seen as a major boost for the city's economy and downtown revitalization efforts.