Demo using [Elections Alberta] ea maps. These maps are already projected by Elections Alberta, they benefit from being "unprojected" before use with topojson. To unproject the map, load it as a vector layer into QGIS and then save the layer to a new file but change the Co-ordinate Reference System to WGS 84 as part of the save action.
Then use topojson like so:
topojson -o albertaNew.topojson -p -q 1e6 <saved file from qgis>
to convert it to topojson format.