One of Twitter's biggest problems is that, while its power users log into the site every day and provide the bulk of its content, many regular people can't work out why the platform is relevant to them.
Twitter CEO Jack Dorsey said in September that Twitter is "the place to see what's happening" - whether that's big world issues, niche topics, or simply what people's immediate communities are doing at that moment in time. These billboards highlight the first of those use cases.
The simple ad displays show single images - portraying guns, transgender issues, the melting of the polar ice caps, Vladimir Putin, the Pride flag, and more - overlaid with the Twitter logo and the hashtag symbol now synonymous with the platform.
The campaign builds on a billboard Twitter erected a few weeks ago near the Lincoln Tunnel in New York, which featured close-up shots of Hillary Clinton's and Donald Trump's eyes.
Writing in a blog post, Twitter's first global group creative director, Jayanta Jenkins, who joined the company in August, explained how the campaign is all part of the company's efforts to help people understand what the platform is used for.
Speaking to Adweek, Jenkins said out-of-home was the best medium to convey this message.