Those districts have been reapportioned. You’re citing Robert Hanrahan from 1972, and he was elected from the pre-1982 3rd, and that’s not the same district the Lipinskis have held. Only a small sliver of the 3rd district of 1972 is in the present day 3rd.
Hanrahan’s 3rd (1972):
https://www.ourcampaigns.com/RaceDetail.html?RaceID=53826
Lipinski’s 3rd (2012-present):
https://www.ourcampaigns.com/ContainerDetail.html?ContainerID=75
Sounds like the RNC dropped the ball.
Only a small sliver of the 3rd district of 1972 is in the present day 3rd.
As the voters move/leave the city, the district lines move with them.