Four Little Rock flights were canceled during the outage.
"Our systems have been fully restored, however we expect continued flight delays and cancellations throughout the remainder of the day," American Airlines said in a post.
The Fort Worth, Texas-based airline earlier in the day had apologized for the inconvenience and said it was working to resolve the issue as quickly as possible.
It had asked the Federal Aviation Administration to issue a ground stop.
The massive grounding of American flights came after a glitch in American's reservation and check-in system, which caused the system the shut for hours.
The carrier has not given a cause for the outage, however, and Sabre, the software maker, has since denied the reports, according to Fox Business.