LOL, Lake Forest voters probably feel like Orange County folks slowly watching diversity slowly make their state/county bluer.
I have several college friends from Lake Forest ... they are not happy about Illinois' standing as a blue state, and their parents almost can't believe the change in the state's politics compared to the '70s and '80s. Orange County is an apt comparison, haha.
IL was never conservative. But it was GOP. However the GOP was deeply corrupt and they were the ones who actually introduced the income tax in 1969 and put public employee pensions in the state constitution also in 1969
The suburbs were much more conservative in the 50s-80s. Rapid suburbanization brought to the area a new upper middle class that had come from little and wanted to protect what was theirs. As the suburbs have matured and this isn't really a phenomena anymore and hasn't been since the 90s when the burbs began a clear trend to the left.
Additionally, the Chicago burbs have diversified somewhat