London startup Citymapper has expanded its mobile navigation app to the San Francisco Bay Area and Chicago, bringing the total number of regions it covers up to nine.

The free navigation app – said to be installed on over half of the iPhones in London and one of the most downloaded apps on iTunes – aims to make it as easy as possible for users to navigate around cities. The app is also available on Android and the web. 

While Google Maps provides some public transportation information, Citymapper aims to go one step further and provide detailed routes with additional information not available from Google.

The rollout to the US cities, issued yesterday as part of the Citymapper 4.8 release, comes after Citymapper users voted which city they wanted the app to cover next.

"We are proud to announce the winners of our voting competition, with gazillions of votes from hundreds of cities around the world," the company wrote in the description of the app update. 

"The top voted city globally is...(lights, theme music, puffs of smoke)...Saaaaan Franciscooooo!... and second place goes to.. (trumpets, beatbox, person on your left gives you a high five)... Chiiiiiiiicaagoooo." 

Citymapper is also available in New York City, Paris, Berlin, Washington DC, Boston, Madrid and Barcelona.

Earlier this year, Citymapper raised $10 million (£6.13 million) in a funding round led by Mayfair-headquartered Balderton Capital, who have also invested in the likes of AirBnB and Lovefilm.

At the time, the Farringdon-based startup, founded three years ago by former Google employee Azmat Yusuf, said it would use the funding to roll out new cities and take on more staff.

Other Citymapper investors included Index Ventures, an investor in Skype and Asos; Connect Ventures, which has funded Secret Sales; and Silicon Valley-based Greylock Partners, an investor in Facebook and Airbnb.