On Friday, Afghan refugees began arriving at Philadelphia International Airport, and elected officials, including Mayor Jim Kenney, have rightly expressed “solidarity with Afghan refugees,” as the city “looks forward to providing them a safe haven.”

Despite the heroic efforts of U.S. military personnel — including the 13 who died in Thursday’s suicide bombing alongside at least 170 of the Afghans they had hoped to protect — there are thousands of Afghans who are still hoping to make their way to safety, and the United States has an obligation to many of them.

» READ MORE: A tale of two Afghan women | Trudy Rubin

Federal officials must place their focus on Special Immigrant Visa applicants — Afghans who assisted the U.S. military and government contractors as translators or in other roles. In the wake of the Vietnam War, the United States offered over 140,000 special visas to Vietnamese who had assisted the country. Experts say roughly 20,000 Afghans were in the special visa pipeline at the start of the evacuation, with potentially 70,000 who are eligible. Beyond the moral obligation of helping those who have helped keep U.S. service members and other Americans safe, there is also a strategic imperative to ensure that in the future, those who work with the United States believe that they have a trustworthy partner.

A second group of particular importance is made up of what federal officials are calling “Priority 1” and “Priority 2” eligible Afghans. Many of these Afghans might have worked for U.S.-based media or nongovernmental organizations in the past, which is enough to garner Taliban attention but not enough for special visa status. The exact number of Afghans who have registered for priority status — or who might be eligible for it — is currently unknown.

» READ MORE: Blood will be on Biden's hands if Afghan allies not evacuated | Trudy Rubin

Religious and ethnic minorities, women’s rights activists, and others are already making plans to flee the country ahead of an Aug. 31 deadline for departures. Forty U.S. senators have sent a letter to Biden administration officials urging them to institute what is called humanitarian parole, which would allow Afghans to complete the visa process in the United States. The Biden administration should listen to them, especially because their refusal to heed voices urging them to speed up the application process months ago has so far led to many being left behind.

Philadelphians should be proud that their city was founded not just because of a geographical confluence of rivers and arable farmland; it is also because of a specific vision and purpose that the city was, as William Penn wrote, “named before thou wert born.” This commonwealth has served as a refuge not only for Penn’s Quakers, but for peoples and faiths from around the world. From German Anabaptists in the 1600s to Kosovar Albanians, Hmong people, and many others in the 20th century, refugees have enriched the fabric of our city and our state throughout our history.

In fact, Philadelphia’s recent population increase, the first in 70 years, was made possible largely because of immigrants, refugees among them. Despite the ravages of a 20-year war, a seemingly endless series of bureaucratic hurdles, and persistent threat of terrorists and suicide bombers, Afghans have made it here. We say, “Welcome home.”