You may not have heard of Basic Income Day, but it’s a rapidly growing event that will prove ever more important with the rise of robot automation. The idea to give everyone a fixed income on top of any earnings seems radical, but supporters believe that as machines take over more human-powered tasks, society will need to cut back on working hours. Basic income would help offset workers’ losses, and on May 1, its proponents are going to take their case to the people.

So far, the movement has seen some success. One Scottish council region has explored the idea, while Finland has become the first European country to try the idea. The Obama administration took a dim view on the idea, instead suggesting an improved social safety net, but Bernie Sanders’ run for president brought the issue to a whole new audience.

The day has rather complex origins, but it stems from the fact that May 1 is also International Workers Day. In the United States, Labor Day is celebrated on the first Monday in September, but in most other countries it takes place on May 1. Marking the strength of workers and trade unions, it seems apt that an initiative aimed at improving lives with the rise of automation would choose the day to celebrate the cause.

“We need the labor unions to support basic income,” Robin Ketelaars, who has served as webmaster for Netherlands-based BasisIncome.nl since 2009, tells Inverse.

In 2009, Günter Sölken, Robert Ulmer, and Günter Schwarz made a post on the German Basic Income Network page, calling on its followers to meet at Berlin’s Wittenbergplatz subway station on May 1 and demonstrate in favor of a basic income.

Two years later, Sylvia Mair teamed up with Oliver Der to design a series of logos and formalize the day:

Participants are encouraged to change their profile picture to these designs. BasicIncomeDay

The movement received a boost in 2013 with the European Citizens’ Initiative for an Unconditional Basic Income. These initiatives enable citizens to call on the European Commission to develop European Union-wide policies. If one million citizens sign the initiative, and the minimum number of signatures is met for at least one-fourth of member states, then it’s passed to the commission to implement.

“I want the world to have UBI,” Ketelaars says. As administrator for the initiative’s online collection system, he helped bring the idea to a Europe-wide audience. Unfortunately, the proposal ultimately received only 285,000 signatures.

“The ECI was already over, but the momentum for basic income stayed,” Ketelaars says. He registered the domain name BasicIncomeDay.org in 2014, and teamed up with Sylvia Mair and Oliver Der to bring Basic Income Day to the world.

That same year, Scott Santens got involved. The moderator of the basic income subreddit, he set up a Thunderclap page to spread the word about the event. Participants pledge to send out a message on their social media accounts, and Thunderclap records how many people saw the message.

The first year Santens set up a Thunderclap, it reached 169,000 people. In 2015, the campaign reached over 700,000. In 2016, Santens got a staggering one million people to see the message. The goal with this year’s Thudnerclap is to reach five million, with a message asking supporters to push their local trade union or city council to back the idea.

“Basic income is the future of the labor movement, and the policy we must all together now strive for in the 21st century,” the message reads.

It’s important to note, though, that Basic Income Day is very much a community-led affair, and its existence has largely gone unnoticed by organized groups. Basic Income New Zealand, the United States Citizen’s Income Trust, and Basic Income Ireland all tell Inverse that they have no plans to commemorate the day.

“To be perfectly honest, we had not heard that May 1st was Basic Income Day,” Anne Ryan, a co-ordinator at Basic Income Ireland, tells Inverse.

Instead, organizations are focusing their efforts around International Basic Income Week from September 18 to 24. The Basic Income Earth Network will hold a conference on September 25 to 27 at the Portuguese National Parliament in Lisbon, with big name economists like Guy Standing and Yanis Varoufakis listed as keynote speakers. The theme of this year’s conference is how to implement a basic income.

With its roots in the people-powered International Workers Day, the Basic Income Day has its support in the grassroots, the community organizers that passionately believe that the policy is the future of labor.

“We can do this. Support is stronger for the idea than ever,” Santens said on his subreddit, rallying followers around the goal to reach five million. “Let’s tell the world about the basic income movement, this subreddit, and how people can learn more and help.”