125th Street's Harlem Happenings app keeps residents and visitors in-the-know on neighborhood history, cultural institutions, storefront vacancies, and real estate news.

In Harlem, the 125th Street Business Improvement District has deployed "ambassadors" with walkie-talkies to assist pedestrians - an average of 950,000 a month - on this main artery packed with stores, restaurants, delis and offices. But to better connect with them and promote the neighborhood's offerings, it introduced an app, Harlem Happenings, in November 2015.