But when Hubby was number crunching about a decade ago, the PCA had the highest member-to-missionary ratio of any denomination (the Southern Baptist Convention had the highest total number of missioaries -- but that denomination is quite a bit larger than the PCA.)

This was limited to missionaries who were affiliated with the PCA sending organization, MTW.   In reality, PCA churches support missionaries from a wide range of sending organizations. 

In many ways, including by not limited to missions, the PCA tends to "punch above its weight."  And so I see a lot of growth than may not necessarily be reflected in membership numbers of a specific congregation or the denomination as a whole.

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