The United States government recently announced a plan to leverage a 100 per cent tariff on "foreign" films. President Donald Trump explained it was because he wanted to protect the U.S. film industry. He said other reasons include "national security" and "propaganda."

The current announcement may seem out of place in trade talks about steel and automobiles. But culture has long been a key part of North American trade relations.

In my book, Trading on Art: Cultural Diplomacy and Free Trade in North America, I examine how culture became a vital tool for shaping relationships among Canada, Mexico and the United States. I focus on visual art - including exhibitions and museum initiatives - to show how culture is intertwined with the negotiation of free trade in North America.

In the late 20th century, when Canada negotiated the Canada-United States Free Trade Agreement (later expanded into NAFTA), culture was central to free-trade debates.

The period was charged with anxiety over American cultural imperialism and concerns about protecting Canadian cultural production. Ultimately, at Canada's urging, culture was formally exempted from free-trade agreements, with limited provisions focused on cultural industries. But even though the cultural exemption in trade agreements may give the impression that culture has nothing to do with the histories of free trade, my research shows otherwise.

This exemption isn't just about protecting markets. Political scientist Patricia Goff says it also comes from a "desire to uphold ...a distinct cultural identity." Culture held a key place in the discussions about the impact of free trade. And it served as a means to construct new geopolitical identities, helping to introduce and reinforce the trade alliance.

Culture was mobilized in different ways. It functioned as a unifying tool, but also a venue for critique.

For example, following the creation of NAFTA, the online exhibition Panoramas: The North American Landscape in Art brought together art from Canada, Mexico and the U.S. The show offered a new transnational approach and explored landscapes across the continent.

Other artworks such as Free Expression by Canadian activist-artists Carole Conde and Karl Beveridge articulated a critical response to impending free trade. Their piece depicts apprehension about the danger of U.S. cultural domination and speaks to the need to protect Canada's cultural producers.

All three governments - of Canada, Mexico and the United States - used art exhibitions as a way to create and share stories about North American unity. While art has long been used for national narratives, this collaboration and these new stories about the North American region were a departure.

For most of the 20th century, people did not think of North America as a unified or shared cultural entity. Most people saw the Americas as divided between Anglo and Latin America.

Art was seen as a means to overcome this. It provided a way to support and depict the new alliance between Canada, Mexico and the United States under free trade. Exhibitions offered a way to depict North America in a new perspective. They presented concepts about continental unity to the public.

How could Canada, Mexico and the United States understand themselves as part of a regional group? These art shows worked on many levels. They brought together work that helped make visual, thematic connections. They helped cultural professionals meet and make connections. They helped museums forge relationships.

On top of that, the exhibitions also provided diplomatic spaces. Many openings celebrated specific moments in bi- and trilateral relationships, creating and facilitating social spaces for diplomatic and government connections.

In this way, these exhibitions functioned as a form of cultural diplomacy. Some were initiated by governments to mark the economic integration of the continent. Others picked up on new understandings of the continent that were circulating. It was a process, according to American historian Nicholas Cull, by which international relationships became managed through the circulation of "cultural resources and achievements."

Art and cultural exchange gave people a meaningful and accessible way to see and understand the growing ties between the three countries. Art also offered a powerful and engaging way to tell the public about North American connections.

These were not the only messages circulating in this period. A body of contemporary art questioned and challenged free trade.

For many Canadian artists, their work offered a means to question and critique increasing economic integration under free trade. In the 1980s and '90s, video art was a particularly active site for such work.

An affordable medium that was easily disseminated, video art critiqued the media coverage of free trade, reflected on cultural nationalism and advanced experimental narratives about North America. Video art was also deeply tied to the anti-globalization protests that began at the start of the economic integration of North America under free trade.

Video offered a space for creative expression and documentation of the protests. Video also enhanced protection for activists who were safer because they were recording their encounters with law enforcement. Beyond producing artworks, many artists joined other cultural producers, community and labour organizations to advocate against free trade.

Free-trade agreements radically reshaped the economies and public understandings of the western hemisphere in the late 20th century. Political scientist Guy Poitras argues that North America as a region was invented at this time.

Culture is often overlooked when considering free-trade histories and dismissed as a form of "soft power." But the cultural sphere does not sit apart from daily life and political economic concerns. Art and exhibitions from this period offer a rich vantage point on how free trade was perceived and contested. Examination of culture also reveals how it was used to construct a North American identity.

Culture is not simply an entity to be instrumentalized for international relations, but a key venue in which these relations always play out. In the lead up to the renegotiation of the Canada-United States-Mexico Agreement and amid the current tariff war, the ties between Canada, Mexico and the United States seem fragile. We should pay attention to how culture will be used as a tool to support or fracture these connections.