WASHINGTON — The U.S. government on Friday extended a ban on nonessential travel along the borders with Canada and Mexico to slow the spread of COVID-19 despite increasing pressure to lift the restriction.

U.S. border communities that are dependent on shoppers from Mexico and Canada and their political representatives have urged the Biden administration to lift the ban. In addition, Canada recently began letting fully vaccinated U.S. citizens enter the country.

But the Department of Homeland Security said in a tweet Friday that the restrictions on nonessential travel were still needed to minimize the spread of COVID-19 and the delta variant. It extended the ban until at least Sept. 21.

DHS said it is working with public health and medical experts to determine how to “safely and sustainably resume normal travel.”

The travel restrictions have been in place since early in the pandemic in March 2020 and repeatedly extended while allowing commercial traffic and essential crossings to continue.