The CDC has been tracking autism spectrum disorders for more than a decade.
Researchers looked at 14 sites across the country, including in Pennsylvania and New Jersey.
The new numbers, taken from 2008, estimate one in every 88 children has been diagnosed as being on the spectrum. That is a 23% rise from the numbers in 2006.
One reason is that the disorder is recognized and diagnosed better.
Dr. Margo Burke of Philadelphia's 'Center for Autism' explained the increase in numbers.
"There are more people that are better equipped to be able to diagnose "We've gotten better at it, and we've been able to diagnose earlier and earlier," said Dr. Burke.
And most experts agree this is at least part of the reason for the increase in numbers. Other experts also say the definition of autism spectrum disorders has expanded to include more kids.
Still the cause of autism remains a mystery. Dr. Burke suspects genetics play a role.
Which would explain why, in the new report, 1 in 54 boys was diagnosed with autism, compared to 1 in 252 girls.
Still she says parents shouldn't worry about the numbers, but should be aware of their children's early development.
"If we catch them early, sometimes we can catch them up on those developmental milestones," said Dr. Burke.
Early intervention is the key to helping them with development.