1. Opening of Oklahoma City Hall: On April 6, 1937, the Oklahoma City Hall, designed by Solomon Layton, opened its doors to the public. The building was a major landmark in the city and served as the city's administrative center for many years.

2. Tornado Outbreak: On April 6, 1978, a major tornado outbreak swept through Oklahoma, causing extensive damage and loss of life. The outbreak produced over 30 tornadoes and claimed the lives of at least 10 people.

3. Oklahoma City Bombing: On April 19, 1995, Timothy McVeigh parked a truck bomb outside the Alfred P. Murrah Federal Building in Oklahoma City, killing 168 people and injuring over 800 others. However, the planning and preparation for the attack began on April 6, 1995.

4. Oklahoman Wins Pulitzer Prize: On April 6, 1984, Edwin Meese III announced that Edith Evans Asbury, of The Oklahoman, had won the Pulitzer Prize for national reporting. She was the first woman from Oklahoma to win the prize, and the first journalist from The Oklahoman.

5. Oklahoma City Thunder Debut: On April 6, 2009, the Oklahoma City Thunder played their first game in Oklahoma City, after relocating from Seattle. The team won its inaugural game against the Sacramento Kings, with a final score of 102-89.