The US Department of Homeland Security said Friday that a COVID-19 ban on non-essential travel through border crossings with Canada and Mexico was being extended until September 21.

The reciprocal travel ban aimed at slowing the spread of coronavirus was first imposed in March and has been extended several times since then.

“We continue to work with our Canadian and Mexican partners to slow the spread of #COVID19,” acting US Homeland Security Secretary Chad Wolf said on Twitter.

“Accordingly, we have agreed to extend the limitation of non-essential travel at our shared land ports of entry through September 21,” Wolf said.

The United States has experienced a recent surge in COVID-19 cases and with more than 5.2 million infections has more than any other country in the world.