Henri de Toulouse-Lautrec, “At the Moulin Rouge: The Dance” (1890), oil on canvas, in the collection of the Philadelphia Museum of Art, which is participating in the 2017 International Museum Day (via Wikimedia)

This Thursday, thousands of museums around the world will offer free or discounted admission, and some are encouraging their visitors to be activists in the process. May 18 is both International Museum Day, organized by the International Council of Museums (ICOM), and Art Museum Day, organized by the Association of Art Museum Directors.

The 2017 theme of the annual International Museum Day is “Museums and contested histories: Saying the unspeakable in museums,” with programming that looks at how these institutions can help us “understand the incomprehensible aspects of the contested histories inherent to the human race.” Meanwhile, Art Museum Day is focusing this year on how “Art Museums Foster Vibrant Communities.” Both themes underline the vital roles museums play in society, whether as places of dialogue or sites of gathering and knowledge. Those roles are threatened in the United States by the Trump administration’s possible plan to defund the National Endowments for the Arts and Humanities and the Institute of Museum and Library Services.

The Philadelphia Museum of Art will have a day of programs to call attention to the issue, with #SavetheArts banners hanging on the building and a postcard-writing station inside for visitors to contact their representatives. The Colby College Museum of Art in Waterville, Maine, will also have a gallery installation of blank museum postcards on a clothesline, available for filling out; after the day is over, the institution will mail them to elected officials. Likewise, the Memphis Brooks Museum of Art is providing postcards (and free admission) for writing to legislators about the personal importance of museums, as are the Missoula Art Museum in Montana and the Portland Museum of Art in Maine.

Even if your local institution isn’t offering free writing tools this Thursday, you could enjoy the galleries on Museum Day and then describe your experience in a letter to your representatives. Our grassroots support of the arts can encourage national policy makers to pay attention to the value of museums.

Full lists of the institutions participating in International Museum Day and Art Museum Day on May 18 are available online.

Allison C. Meier is a former staff writer for Hyperallergic. Originally from Oklahoma, she has been covering visual culture and overlooked history for print...