DNC keynote speaker and San Antonio Mayor Julian Castro says the country is "better off now" than when President Obama took the oath of office on Jan. 20, 2009.

"Folks ought to remember that when he took office - and we're talking about being on the brink of a great depression, losing between 750,000 and 800,000 jobs that month of January 2009 - the economy was in a free-fall," Castro said. "Nobody is saying that we're where we need to be, but it is a world away - a lot of progress from where we were."

ABC News' senior political correspondent Jonathan Karl interviewed Castro and his twin brother, Joaquin, a candidate for the House of Representatives, on ABC News / Yahoo News' Democratic National Convention show in Charlotte on Thursday evening.

Castro urged Obama to "not back away from the idea that the nation is in a better place."

"Folks should remember that there were very strong headwinds because he inherited an economy that was in a free-fall," he said. "The nation is lifting up. It's rising, it's progressing, but that's slow progress, but it is progress."

"Folks traditionally start paying attention more to the election after Labor Day," Castro continued. "I'm confident that you're going to have folks out there who are enthusiastic, who have seen the progress that we have made, believe in the president and that he's going to win on November 6th."