Maybe somebody on the internet has already tackled this all-important question and so I googled up What Happened To DeSoto Dealers.
The first result that comes up is the
Wikipedia page on DeSoto, with a separate paragraph "Dealer Networks" offering this thought:
"However, as Chrysler attempted to spin Plymouth off into standalone dealerships, existing dealers typically chose to become higher-volume Plymouth dealerships rather than taking on the slower-selling DeSoto brand, leaving the marque with a weakened dealer network and fewer outlets selling its cars."
So there should be a correlation between the diminishing number of DeSoto franchises and the growing number of Plymouth-only dealerships. Let's see!
DeSoto total franchises vs. Plymouth exclusives
1 January, 1956: 2,610 vs. 000
1 January, 1957: 2,454 [-156] vs. 077 [+77]
1 January, 1958: 2,256 [-198] vs. 195 [+118]
1 January, 1959: 2,053 [-203] vs. 176 [-19]
1 January, 1960: 1,846 [-207] vs. 252 [+76]
Do you see it? I don't! The loss of DeSoto franchises follows a steady course of its own, accelerating somewhat toward the end.
We have already seen that the +76 Ply-only during 1959 is largely due to the Dodge-Plymouth divorce.
Especially the development during 1958 shows the discrepancy between the two number series. The loss of 19 Ply-only dealerships in no way reflects in an interruption in the decline of DeSoto franchises.
That's not to say that there haven't been DeSoto-Plymouth duals that shed DeSoto in order to become Plymouth-only, but it had little impact on the total number of DeSoto franchises.
Whereas the
quotes in the first post underrate the importance of Ply-only outlets, the Wikipedia quote attaches far too much importance to them.