For better or worse, a lot of people get their news primarily from Facebook. The social network is aware of this, and earlier this year, started testing a feature called Today In, which brings curated local stories to users. The feature is apparently progressing well, as Facebook has announced that it's now available in more than 400 cities around the United States.
Today In has its own section in the Facebook app, and aggregates stories and events relevant to users in a specific cities. You can also choose to have content from the section appear in your normal News Feed. Facebook has also started testing Today In for "news deserts" without much in the way of local journalism; once the feature is available in those areas, Today In will show news from nearby communities. Testing is also underway in Australia.
Additionally, Facebook has started testing giving local authorities the ability to mark their posts in both the News Feed and Today In as local alerts. Local authority and first responder pages in the test can mark up to 35 posts as local alerts per 30-day period; this doesn't affect the posts' ranking, but is meant to help distinguish them from other content. These pages can also send users in affected areas push notifications. Facebook says the new features aren't meant to replace traditional emergency alert services, however.