This document discusses how cities can become smarter by analyzing and visualizing spatial data. It provides examples of how real-time traffic and transportation data, real estate data, and business directories can be used. Specific projects are described that used data to streamline taxi supply and demand, improve taxi passenger safety, and allow residents to report local issues. The document advocates for cities to promote open data, foster data literacy, and cooperate with civic hackers to make productive use of data and spatial analysis to inform decision making.