Am I underpaid? (RN)

I have been an RN for 13 years with the same hospital network in Indiana. My starting pay in 2011 was $21.75/hr. 13 years later I am now at $41/hr. This was a second degree and career change for me so I am older and I currently work with a lot of young girls who I suspect are making the same amount as me. I’ve never asked as we are not close. I have an ASN but a Bachelors degree in another field. Am I being underpaid?