One way to promote a regional use app is to use local mobile advertising. Some apps are for national or international use. Some are for local use. Think of the difference between a national television broadcasting company and a local network affiliate. The national broadcaster can run adds for an app they make for their consumers anywhere in the country. The local broadcasting affiliate would just be wasting their money with a national advertising campaign. They need to target local consumers to download their app.
Sticking with the example, the national broadcaster might have an app where you can learn about the shows they broadcast and do all kinds of other fan stuff. They might have stories about upcoming shows or new seasons and things like that. Local stations usually have their news show heavily promoted on an app. The apps usually include a weather feature with warnings for local users and news highlights for the region served. The people served by the local TV station are the consumers you would want to target with local mobile advertising. This would put your ad on other apps that are relevant and on mobile websites too.
Apps are big moneymakers no matter how you use them. A local TV station wants to keep their viewers engaged at home and away from home. You want them returning to you to get their news fix so they see your advertising that is paying all of the bills. Your advertising is on websites, in the app and on commercials during TV shows. The thing is, more and more people are consuming TV through mobile devices. You need an app for quick access to headline news events for people not at home. To get these consumers to use your app, whether it is for TV or restaurant app that is regional instead of national, you need to get the word out using local mobile advertising.