HB 18821 Schwinn Chicago made Pre-1970's bicycle?

I recently bought a 1950s-1960s made original women's Schwinn bike. I found the serial number, HB 18821, on the left side of the back tire axle, which indicates the era it was made. It's got the original seat, and the only thing that's 'new' are the pedals. I'm wondering what model it is, since I can't find ANYTHING with this serial number, what exact year it was manufactured, and ultimately what I can get for it?