I can't seem to find the other states that do keep them

Here are a few I found in an article

[link to www.washingtonpost.com]

Each state determines what is done with the blood spots afterward. The District discards them after a year. Virginia saves them for up to 10 years but does not allow them to be used for research, officials said. Maryland has been storing blood spots since 2004 and may make its inventory of about 350,000 samples available to researchers. At least nine other states also keep the blood spots indefinitely.