There are currently no reliable sources of trend data for King Rail in Canada, as it is a rare and secretive marshbird that is detected too infrequently by most surveys to accurately derive trend estimates. At the continental scale, both the Breeding Bird Survey and Christmas Bird Count indicate a large, long-term decline, but these reflect the larger population in the United States and neither source provides trends specific to the Canadian population. Observations from the Great Lakes Marsh Monitoring Program have also been too sparse for changes over time to be quantified. Incidental records and isolated observations in marshes throughout southern Ontario suggest a decrease since the 1970s, from no more than 300 pairs (an estimate which has since been described as being inflated) to possibly fewer than 50 pairs by the late 1990s (James, 2000), but there is insufficient information available to assess the current national status relative to the 1970s.

The national goal for King Rail is to maintain stable populations of the species throughout its Canadian range. This is based on the Recovery Plan for King Rail under the Species at Risk Act. Monitoring data are insufficient to assess the status of King Rail relative to this goal.