May 21 is an important day in Pennsylvania history. Here are five interesting facts about this day in the Keystone State's history:

1. In 1787, the Pennsylvania state convention ratified the U.S. Constitution. Pennsylvania was the second state to do so, after Delaware, and the ratification helped to pave the way for the creation of the United States of America.

2. In 1879, the Johnstown Flood occurred in Pennsylvania. Heavy rains caused the South Fork Dam to fail, sending a wall of water down the Conemaugh Valley and devastating the towns of Johnstown and surrounding areas. Over 2,200 people lost their lives, making it one of the deadliest natural disasters in American history.

3. In 1949, the first NASCAR race was held in Pennsylvania. The race took place at the Langhorne Speedway, which was located just outside of Philadelphia. NASCAR has since become one of the most popular sports in the United States, with millions of fans across the country.

4. In 1991, the first episode of the television show "Mystery Science Theater 3000" premiered on television. The show was created by Joel Hodgson and was produced in Minnesota, but many of its writers and actors were from Pennsylvania, including Trace Beaulieu, Frank Conniff, and Mary Jo Pehl.

5. In 2002, the first Harry Potter book was translated into Pennsylvania Dutch. The translation, titled "Harri Pott un di Wunnerstu" (which roughly translates to "Harry Potter and the Wonderful"), was done by linguist Horst Schaefer and was a popular hit in Pennsylvania Dutch-speaking communities.

These are just a few of the many interesting events that have occurred on May 21 in Pennsylvania history. From politics to sports to pop culture, this day has seen its fair share of excitement and significance.