Political activism can be measured in several ways: by the number of signatories on a petition, demonstrators at a protest or donations to an organization.

Or, in some cases, the sale of art supplies.

The week before the Women’s March on Jan. 21 in cities across the United States, protesters who were making signs helped fuel increased sales of poster boards by 33 percent and foam boards by 42 percent compared with the same week last year, the consumer research group NPD reported recently. Poster and foam board sales from Jan. 15 to 21 totaled $4.1 million.

More than 6.5 million poster boards were sold in January, with nearly one-third sold during the week of the march. Sales of easel pads and flip charts grew by 28 percent, Leen Nsouli, an office supplies industry analyst at NPD, said in a blog post.