You may find an answer on the website for the school district where you'd like to send your child. Look for enrollment guidelines/policies, out-of-district transfer policies, etc. There may be a page somewhere on the site that provides the information - if not, there will be a department directory with phone numbers that will point you in the right direction. You will probably need to call the Student Services department, an assistant superintendent's office, or something along those lines.
For example, on the Pittsburgh Public Schools website, there is a link at the bottom of the home page for both "Enrollment" and "Contact Us."
I hope you find the information you're looking for - good luck to you!