San Antonio Mayor Julian Castro delivered a keynote that was a mix of attacks on Mitt Romney, praise for President Obama, and the story of his own family's path from Mexico to America. 

"In the end, the American dream is not a sprint, or even a marathon, but a relay," Castro said. "Our families don't always cross the finish line in the span of one generation. But each generation passes on to the next the fruits of their labor. My grandmother never owned a house. She cleaned other people's houses so she could afford to rent her own. But she saw her daughter become the first in her family to graduate from college. And my mother fought hard for civil rights so that instead of a mop, I could hold this microphone."

As Castro spoke, members of the Texas delegation cheered from the back of the hall, waving signs that read, "Castro Country" and chanting "Julian! Julian!"

But the delegation cheered even louder when Castro's mother, Rosie, appeared on the Jumbotron above the crowd. And as Castro spoke about bringing his young daughter to her first day of pre-kindergarten, one delegate broke into tears. 

"It was just so touching," she said afterward, declining to give her name.

Here's more on Castro and his brother Joaquin, who is running for Congress.