It occurs to me that I have never addressed the issue on this blog.

Basically, maps online are not accessible.  According to Treasury Board, this is because the image of the map needs a longdesc attached to it in order to meaningfully describe the map.  This can easily be found right at the beginning under checkpoint 1.1 in the W3C Web Content Accessibility Guidelines:

1.1 Provide a text equivalent for every non-text element (e.g., via “alt”, “longdesc”, or in element content). This includes: images, graphical representations of text (including symbols), image map regions, animations (e.g., animated GIFs), applets and programmatic objects, ascii art, frames, scripts, images used as list bullets, spacers, graphical buttons, sounds (played with or without user interaction), stand-alone audio files, audio tracks of video, and video. [Priority 1]
For example, in HTML:
  • Use “alt” for the IMG, INPUT, and APPLET elements, or provide a text equivalent in the content of the OBJECT and APPLET elements.
  • For complex content (e.g., a chart) where the “alt” text does not provide a complete text equivalent, provide an additional description using, for example, “longdesc” with IMG or FRAME, a link inside an OBJECT element, or a description link.
  • For image maps, either use the “alt” attribute with AREA, or use the MAP element with A elements (and other text) as content.

The creation of a map requires a multitude of data, raw data that the viewer never sees, only in its graphical form.  How do we turn that raw data into a meaningful text description, as well as include information that we automatically infer when viewing the map?  The data behind interactive maps is constantly changing as you pan, zoom, turn on/off layers etc, the text description will need to be dynamic in order to address this.