(WWTI) — The United States border will remain closed to Canadian travelers.

The U.S. Department of Homeland Security tweeted on Friday that the country is extending restrictions on non-essential travel with Canada and Mexico through September 21. This was announced one day before the restrictions were set to end on August 21.

According to the DHS, this extension is to minimize the spread of COVID-19, including the Delta variant. Restrictions apply to non-essential travelers from Canada and Mexico at land and ferry crossings.

Canada recently opened its border to American travelers on August 9. This allowed non-essential travelers to enter to country under certain guidelines.

Non-essential travel has been restricted since the start of the COVID-19 pandemic in March 2021.