What makes for a capital of USA state as Balanced State of Capital?

Question

If the capital city of a US state conforms to a special rule, I identify it as having a Balanced State of Capital™. As it turns out, only 8 of the 50 state capitals qualify for this Balanced State.

Those 8 state capitals, in alphabetical order, are:

Atlanta, GA
Boise, ID
Juneau, AK
Nashville, TN
Phoenix, AZ
Richmond, VA
Sacramento, CA
Topeka, KS

What rule defines these each as Balanced State of Capitals?

Answer 1

Their city name has the same number of letters than their state name.