You're in luck, Joel, the shapefile you need is available here: http://opendata.dc.gov/datasets/0ef47379cbae44e88267c01eaec2ff6e_31
The next step is use QGIS to convert this data into a format usable for Tableau. Here's a tutorial if not: https://community.tableau.com/docs/DOC-5831). The resultant file can be used to overlay ward boundaries over a map of DC.
Thanks for the quick response. I appreciate it.