"Happy heavenly birthday to Rush," David Limbaugh tweets. "He would have been 74 today. His fans remain the best and the loyalist. You know who you are. Thank you."

"My friend Rush Limbaugh would be 74 today," tweets Erick Erickson. "He pushed me to get behind a microphone and try radio. I wouldn't be doing what I'm doing but for him and I miss him."

Rush Limbaugh's commentary still speaks to this day, even after he is passed. His unique amplification of overlooked or non-mainstream areas of national news, politics and culture is still felt. The onslaught of vitriolic criticism he received with unhealthy frequency and his not yielding to the temptation to conform and compromise to media norms are two ways Rush Limbaugh stands out.

We may never know just how deep is the Rush Limbaugh imprint on our nation's skull.