Some interesting info here on a CDC study about differences in treatment for children aged 2-5, diagnosed with ADD/ADHD.
Medication as a treatment is clearly popular in Appalachia/Mid-South (Kentucky, Tennessee, Arkansas, Louisiana, Oklahoma etc.). Whereas psychological treatment is a much more prevalent solution in California, the upper-Mid-West (Wisconsin, Michigan, Illinois, Minnesota). Though not all states have sufficient information.
There is also regional variation depending on if the children are insured through a parent's employer or through Medicaid. All the children in the study were insured.
https://stacks.cdc.gov/view/cdc/39039