No, Those Stars Couldn't Have Died Millions of Years Ago
Whenever I looked up in the night sky, I thought to myself, "Wow, it's amazing that these stars could've been dead for millions of years now and we'd have no idea." Today, inspired by this xkcd comic, I set out to do some research to find out how wrong I am.
Using data from here, I made this graph:
To my surprise, the stars I see in the sky are never more than 3000 light years away.* The mean average distance of the 300 brightest stars is 347 light years, and the median is 185. "These stars could've died before the Civil War and we'd have no idea" really doesn't pack quite the same punch.
Also, interestingly, there's no correlation between brightness ranking and distance from Earth (r-squared of 0.0003).
*The data features the 300 brightest stars in the sky at night. My assumption is that I don't see many more than 300 stars at night in the urban areas where I live.