Photo taken on Jan. 2, 2019 shows the Smithsonian Institution Building in Washington D.C., the United States. The 19 Smithsonian museums and the National Zoo in Washington D.C. closed their doors on Wednesday as the partial US government shutdown dragged on. (Photos: Xinhua)

Photo taken on Jan. 2, 2019 shows the Smithsonian Institution Building in Washington D.C., the United States. The 19 Smithsonian museums and the National Zoo in Washington D.C. closed their doors on Wednesday as the partial US government shutdown dragged on.

Photo taken on Jan. 2, 2019 shows the Smithsonian Institution Building in Washington D.C., the United States. The 19 Smithsonian museums and the National Zoo in Washington D.C. closed their doors on Wednesday as the partial US government shutdown dragged on.

Photo taken on Jan. 2, 2019 shows the Smithsonian Institution Building in Washington D.C., the United States. The 19 Smithsonian museums and the National Zoo in Washington D.C. closed their doors on Wednesday as the partial US government shutdown dragged on.

Photo taken on Jan. 2, 2019 shows the Smithsonian Institution Building in Washington D.C., the United States. The 19 Smithsonian museums and the National Zoo in Washington D.C. closed their doors on Wednesday as the partial US government shutdown dragged on.

Photo taken on Jan. 2, 2019 shows the Smithsonian Institution Building in Washington D.C., the United States. The 19 Smithsonian museums and the National Zoo in Washington D.C. closed their doors on Wednesday as the partial US government shutdown dragged on.

Photo taken on Jan. 2, 2019 shows the Smithsonian Institution Building in Washington D.C., the United States. The 19 Smithsonian museums and the National Zoo in Washington D.C. closed their doors on Wednesday as the partial US government shutdown dragged on.