Streetmix is an online tool that lets you play with street design, allowing you to widen sidewalks, add public transportation, move around bike lanes, and more. Created by a small team of fellows at Code for America, a non-profit dedicated to finding ways to apply modern technology practices to city governments, the app allows players to imagine their dream streets and partake in the urban design process. 

The idea came about when Lou Huang, back in 2013, attended a community meeting about redesigning a street in San Francisco. To help brainstorm ways of improving the corridor, planners handed out paper cutouts, allowing participants to visualize their ideas. Huang, who was an urban designer at the time, got the idea that this exercise would make for a great web-based application where citizens and planners  alike can mockup city street designs.

Streetmix lets users redesign a street by dragging elements around the screen. Through the online tool, users are able to edit and arrange design features ranging from street width and planting strips to bus shelters and sidewalk lamps. The system will choose defaults—like lane direction, proper bus shelter orientation etc.—but users are free to adjust them as they please.

Inspired by SimCity, the online tool is meant to encourage users to get interested in urban design and/or advocacy. And since its founding, it has actually been employed to propose improvements and ideas for actual streets in a number of cities. The app has been used by Sioux Center, Iowa residents to protest the widening of highways; by cycling advocates like Wellington Region Cycleways to propose adding bike lanes; professional city planners looking to quickly sketch some ideas; and has even been forked into Spanish for Mexico city planners!