Gabe Klein, with credit-card parking meters in January 2010. (By Mark Gail/The Washington Post)

Klein made an announcement on his personal Web site:

I am excited for a new exhilarating adventure and to serve the wonderful people of Chicago (I am amazed at how friendly everyone is here btw). ... This is an opportunity to continue public service in the 5th largest urban economy in the world, for a leader every bit as reform-minded and results oriented as former DC Mayor Adrian Fenty; to make Chicago an example nationally for innovation in transportation and public space, and most importantly, to positively impact quality of life for the 2.6 million residents of Chi-town.

Klein declined further comment, pending conversations with the Chicago aldermen who will be overseeing his confirmation.

Emanuel announced Klein’s appointment this morning, along with a new leader for the Chicago Transit Authority. Emanuel takes office May 16.

Klein, who had no background in government before Fenty selected him in late 2008, became a zealous advocate for pedestrians, cyclists and transit users as head of the District Department of Transportation. He debuted the massively successful Capital Bikeshare, oversaw expansion of the city-run Circulator bus service and was a prime evangelist for development of streetcar lines — which has been rewarded with a $99 million proposed investment in Mayor Vincent C. Gray’s recent budget plan.

Klein will now head a much larger department in a much larger city, though it is a demotion in one sense — DDOT was a state-level department, dealing directly with federal funders. In Chicago, he’ll be dealing with a melange of state and local authorities, including the state transportation department and the CTA.

But Klein will have a boss who espoused during his campaign an idea of transportation very much in keeping with Klein’s, as part of a broader vision of urban development. Emanuel has committed, for instance, to building 25 miles of bike lanes per year. A source with knowledge of Klein’s job search said he had turned down offers to run state transportation departments before saying yes to Emanuel.

There is one thing Klein won’t have to worry much about: parking meters. Emanuel’s predecessor, Richard M. Daley, famously sold 75 years worth of the city’s parking meter revenue for $1.2 billion in 2008.