The only long-term source of information on the population status of Long-billed Dowitcher is migration monitoring by the Program for Regional and International Shorebird Monitoring (PRISM). However, relatively few sites record this species regularly, and analysis is complicated by the close resemblance and geographic overlap between Short-billed Dowitcher and Long-billed Dowitcher, therefore overall reliability of PRISM migration monitoring data is considered low. The data indicate a large, gradual, long-term decrease in abundance, with most of the decline occurring since the early 2000s. The population is currently almost 80% lower than in the early 1980s.

The goal for Long-billed Dowitcher is to increase the population to the level it was at in the early 1970s, based on the Breeding Bird Survey. Trend data show that Long-billed Dowitcher is far below its goal range and its population decline is ongoing. The trend will need to stabilize before the population can begin to rebound, and it is not realistic for the goal to be met by 2050. Based on analysis of the historical population loss and potential growth rates, the interim target is to reach 30% of the goal by that year. Achieving this target, and ultimately reaching the national goal for this species, will require ambitious and long-term conservation action.