Two months after the Smithsonian successfully reopened the National Zoo and the National Air and Space Museum’s Steven F. Udvar-Hazy Center in Chantilly, Va., four more museums will welcome back visitors on Friday.

The Smithsonian American Art Museum, the National Portrait Gallery, the National Museum of African American History and Culture and the Renwick Gallery are the next sites in the gradual reopening of the world’s largest museum complex. The success of the zoo and Udvar-Hazy gave the Smithsonian confidence to introduce more, Smithsonian Secretary Lonnie G. Bunch III said.

“We have not had any infections of staff, which means our safety protocols are working,” he said, citing his first priority.

Social distancing guidelines, including signage on the floors and public address announcements, have worked, Bunch said, while concerns about potential resistance to wearing masks proved unfounded.

About 45,000 people have visited Udvar-Hazy since July 24, when the Smithsonian also reopened the zoo, which has welcomed about 170,000 visitors. The Hirshhorn Museum’s Sculpture Garden and other Smithsonian gardens opened Aug. 17.

Procedures similar to those in place at the zoo and Udvar-Hazy will help to protect the health and safety of the staff and visitors. They include reducing hours, limiting capacity and requiring visitors to obtain free, timed passes for three of the four sites. About 1,100 passes a day will be distributed for the American Art museum and Portrait Gallery, which share the historic Patent Office Building in Penn Quarter. About 250 a day will be available for the African American Museum.

The museums will require visitors ages 6 and older to wear face coverings and to stay distanced. One-way paths and directions will help control the flow of guests, and hand-sanitizing stations will be plentiful. Visitors who are sick or do not feel well are asked to stay home.

The Smithsonian closed its network of museums and the zoo on March 14 as part of the effort to reduce the spread of the novel coronavirus. The rest of the Smithsonian sites remain closed.

The four museums will be open Wednesdays through Sundays, but their hours will differ. The National Museum of African American History and Culture on the Mall will be open from 11 a.m. to 4 p.m., while the American Art Museum and the National Portrait Gallery will operate from 11:30 a.m. to 7 p.m. (Visitors must use the G Street NW entrance.) The Renwick’s hours are 10 a.m. to 5:30 p.m.

Free, timed passes for the American Art Museum, National Portrait Gallery and African American Museum are available at si.edu/visit or by phone at 800-514-3849, Ext. 1. Individuals can reserve up to six passes; each visitor, regardless of age, must have one. Groups are capped at six, and there must be at least one adult with children younger than 18. The smaller Renwick, near the White House and home to the Smithsonian American Art Museum’s decorative arts collection, will not require passes.

Stephanie Stebich, the director of the American Art Museum, is eager to have visitors return to the galleries.

“People are suffering, and I believe we are in the art and people business,” Stebich said. “Artists give us hope, seeing some of our favorite objects, being in places that are familiar to us, doing things that we enjoy — we have to get back to those things.”

The museums’ cafes and retail shops will not be open, and public tours and events are suspended. In addition, some exhibits and spaces may be closed or operated at limited capacity. For example, the African American Museum’s Oprah Winfrey Theater remains closed, as does the segregated Southern Railway Car and Edisto Island Slave Cabin. Many of that museum’s popular exhibits, including the Follow the Green Book and Segregated Lunch Counter interactives and the reflection booths, remain closed.

The Smithsonian has adopted a cautious approach that has been informed by D.C. and federal guidelines. At the moment, Bunch said the data show that reopening these facilities is an acceptable risk.

“This is going to be the new normal,” Bunch said. “At a time of pain, we need institutions that remind us of beauty. At a time of divisiveness, we need museums to remind us we’ve been through this before. For me, it’s about public service.”