Gas drilling critics gathered by the hundreds for a rally Wednesday outside the Arch Street entrance of the Pennsylvania Convention Center.
Inside the center, leaders of the Marcellus Shale industry were opening a two-day conference to promote shale-gas development.
"We're going to show this industry how strong we are and how unacceptable gas drilling is," said Iris Marie Bloom, founder of Protect Our Waters, who organized the rally.
She told the crowd that "we are 65 organizations strong. You look beautiful."