The extensive use of GPS-based travel surveys in the past few years now allows vehicle movements to be traced and, thus, data on the actual routes chosen for various trips to be collected. However, efforts on the empirical modeling of route choices through the use of GPS traces are still limited. In this context, the broad focus of this research was to combine data from a large-scale GPS-based travel survey and geographic information system-based roadway network databases to develop models for route choice. Data from GPS streams for 1,913 trips were used in this analysis. Three models that considered choice set sizes of five, 10, and 15 alternatives were built. The estimation results indicated statistically significant and intuitively reasonable effects of free-flow travel time, left turns, right turns, intersections, and circuity on the attractiveness of different route alternatives. Furthermore, the sensitivity to these factors was found to vary on the basis of trip (purpose, time of day, and day of the week) and traveler (gender, age, and length of stay at the current home) characteristics.