Scientists, researchers, and concerned citizens alike took to city streets on Saturday for the 2018 March for Science demonstration.

The annual event, which was introduced in 2017, aims to encourage the world’s lawmakers to use science-based evidence when implementing policies.

“Science advocacy should not be limited to times when our country faces crises or focused only on change at the federal level,” the march’s official website reads. “It is our responsibility to hold all policy makers—from school board members to mayors to the president—accountable for developing and enacting evidence-based policy. Much of this guide is specific to the U.S. government. We are working with organizers around the world to put together guides to encourage advocacy in all countries.”

This year’s main march took place outside the National Mall in Washington, D.C, with more than 230 satellite events scheduled worldwide. Cities like NYC, Munich, Abuja, and London took part in this year’s demonstration; however, some U.S. participants said the 2018 march had a noticeably smaller turnout than the inaugural event.

“There definitely aren't as many people present this year,” Mackenzie Mittleman told CNN, “but the people and speakers here are equally as passionate to help advocate for science.”

You can check out videos and photos from this year’s demonstrations below. To learn more about the event, go to March for Science’s official website.