Unleaded gas?

Why do gas stations still advertise gasoline they sell as "unleaded gas"?  It has been decades since they have been able to sell leaded gas, and as far as I know, there isn't a place to buy leaded gas any more.  So, is the "unleaded" label really necessary?

I do know some people who put lead additives in their car as they run some ancient wreck and can't get leaded petrol anymore. I suppose it is just a name which has stuck. Also I think it is maintain a distinct difference between that and diesel. Although I've been to other countries which call Unleaded petrol "Super Gas".

Super gas?  That's pretty funny. 

When I lived in the north, our cars did not make it to be that old, so we didn't have a problem with older cars needing things that aren't available.  Since I moved south, I see lots of very old cars.  Makes me wonder if they had to be modified to take the unleaded stuff.