The development of applications for mobile devices is becoming an important job creator and contributes more than $632 million annually to Pennsylvania's economy, ranking the state among the top in the nation for the industry, according to the trade group Application Developers Alliance.

The study, titled “The Geography of the App Economy,” places Pennsylvania 11th in the nation for app-development jobs, with about 12,900 in the state. The state’s economic impact of app development makes it 10th in the nation, according to the study.

However, Pennsylvania falls to 19th when measured by “app intensity,” or the number of app jobs as a percentage of total employment, according to the study.

The alliance highlighted two Pennsylvania companies in its promotion of the study, Scranton-based Appek and Lancaster-based appMobi, as examples of the growing impact on jobs and the economy.

“While many people think that technical innovation only happens in Silicon Valley, there is a surprising depth of quality engineering talent in Pennsylvania, and appMobi has been fortunate to hire from this pool of skilled developers,” appMobi CEO David Kennedy said in a statement. Kennedy also is a member of the alliance’s board of directors.

Nationally, app development is responsible for about 519,000 jobs and billions in economic impact, according to the study.

Technology jobs are increasing but there’s a shortage of qualified workers, midstate companies said earlier this year.

The Washington, D.C.-based alliance partnered with CTIA-The Wireless Association, a trade group representing the wireless communications industry, to conduct the study. D.C.-based research and consulting firm South Mountain Economics completed the study for the organizations.