(CNN) On a rainy Saturday in Philadelphia, as the partial government shutdown continued, volunteers picked up trash outside Independence Hall, birthplace of the Declaration of Independence and the Constitution.

Across the country, dozens of their colleagues in the Ahmadiyya Muslim Youth Association were doing the same at national parks closed or partially closed by the shutdown. They cleaned up litter, emptied garbage cans and swept the grounds -- from the Everglades National Park in Florida to Joshua Tree, California and the Cuyahoga Valley, Ohio.

More than a dozen young men with ⁦@MuslimYouthUSA⁩ are cleaning up Independence Mall today in pouring rain. They say they are doing their part in helping amid government shutdown. pic.twitter.com/xxTvyubo9W — Claudia Vargas (@InqCVargas) January 5, 2019

The group hit the National Mall in Washington on Sunday morning.

"Service to our nation and cleanliness are important parts of Islam," said Dr. Madeel Abdullah, president of youth group, in a press release. "We could not sit idly by as our national parks collected trash. We will lead by example and dispose of this garbage appropriately and invite all Americans to join us in these parks and others across the nation."

Group members were joined by people from the general public who contacted the group through social media, spokesperson Salaam Bhatti told CNN, adding that the response to their efforts has been "overwhelmingly positive."

Read More