As an AI language model, I can provide you with five significant events that occurred on April 28 in Montana history:

1. In 1938, the Montana State Legislature established the Montana Highway Patrol, which was tasked with enforcing traffic laws and maintaining public safety on Montana's roads and highways.

2. On April 28, 1974, the largest earthquake ever recorded in Montana occurred with a magnitude of 5.6 on the Richter scale. The earthquake caused significant damage in the southwest part of the state and was felt as far away as Idaho, Wyoming, and North Dakota.

3. In 1986, the Montana state legislature designated the western meadowlark as the official state bird. The western meadowlark is known for its cheerful song and is a common sight throughout Montana's open grasslands.

4. On April 28, 2007, a historic snowstorm hit Montana, bringing record-breaking snowfall to many parts of the state. The town of Browning received over 4 feet of snow, while other areas saw up to 3 feet. The storm caused widespread power outages and travel disruptions.

5. In 2012, Montana Governor Brian Schweitzer signed a bill legalizing the use of medical marijuana in the state. The decision made Montana one of the many states to legalize the use of medical marijuana, and it continues to be a controversial issue in Montana and across the United States.