More than 600 Porto city buses and taxis have been fitted with routers to provide free Wi-Fi service. It's being touted as the biggest Wi-Fi-in-motion network in the world. Sérgio Rodrigues/Veniam hide caption

The sun sets as a visitor uses his mobile phone Monday during the opening day of the 2015 Mobile World Congress in Barcelona. Wall Street Journal reporter Ryan Knutson — interviewed from the conference Monday via Skype by NPR's Robert Siegel — says that for some smartphone users, Wi-Fi may be able to replace most of the functionality of a cellphone carrier. Josep Lago/AFP/Getty Images hide caption

"I knew why they chose Rosa" Parks instead of her as a symbol of the civil rights movement, Colvin says. "They thought I would be too militant for them." Julie Jacobson/AP hide caption

Members of the Muslim community leave the East London Mosque after prayers before the start of the holy month of Ramadan in June 2014. The mosque has an estimated 7,000 worshippers. Rob Stothard/Getty Images hide caption

About 1 in 3 patients with dementia who live in nursing homes are being sedated with antipsychotic drugs, the GAO says. Outside nursing homes, about 1 in 7 dementia patients are getting the risky drugs. Wladimir Bulgar/iStockphoto hide caption

Mikulski (left) and her then-opponent Linda Chavez hold hands before the Maryland Senate candidates debate in 1986. J. Scott Applewhite/AP hide caption

Arizona commission attorney Mary O'Grady (left) and Stephen Miller, a city council member, point to a possible redistricted map in 2011. Ross D. Franklin/AP hide caption

Workers stand next to a gas pipeline not far from the central Ukrainian city of Poltava in June 2014. Ukraine imports much of its gas from Russia, which is once again threatening to cut off supplies in a dispute over payments. Sergei Supinsky/AFP/Getty Images hide caption