During the 1952 thru 1966 time period the Chicago metro area was still rather sparsely populated in far west and southwest suburbs of Chicago. In that time frame these areas were probably considered as an Exurb. Were WCFL stated to have problems was during the 1968 thru 1993 era that experienced tremendous population growth in Will County (southwest) and Kane County and the western half of Dupage County (west).WCFL's night signal certainly hurt the White Sox between 1952 and 1966 and the Cubs became more popular downstate and in Iowa. Oddly, the White Sox became very popular in Buffalo, NY, 500 miles to the east.
When I was growing up in Boston, WCFL was by far the strongest signal from the Chicago area at night. 720 was overpowered by WOR from NYC and French CKAC Montreal. 670 was toast between WNBC and WNAC/WRKO Boston. 780 was between WABC NY and WEAN Providence and 890 just didn't do well in Boston.
In current times, WMVP (Disney) had rebuilt the Downers Grove transmitter site in 2006 with a dog leg array that help to improve coverage to the north/northeast suburban areas but as a result seemed to deepen the null towards the southwest that always existed to protect Oklahoma City and Mexico City at night. There is a WMVP HD2 carried on 100.3 FM which Good Karma leases from Hubbard but not sure how the many people in the Chicago area have access to HD radio. There is always the streaming App which can be accessed on a smart phone and used with Apple Car Play or Android Auto. Good Karma believes that streaming Apps are their future not over the air radio.
The WMVP relocation to the WCPT night site in Joliet appears at least on paper to solve some of the reception issues in southwest DuPage and northern Will counties that are highly populated that were experiencing the deep null with the previous night pattern from the old Downers Grove site. At issue now is what is probably a weaker day and night signal in the far North and Northwest suburbs now that the Joliet diplex site has been active for close to six months now. My guess is that WMVP is still listenable in the far north and northwest area but with increased background noise and probably some selective fading due to the shorter 298 FT towers at the WCPT/WMVP Joliet diplex site.

