Southern California Cadillac

For those of you who remember the classic "Hey Arnold" cartoon series that used to appear in Nickelodean back in the 1990’s:
I find it hard to comprehend exactly what time period the show is set in.
I noticed that most of the people in Hillwood City drive around in old Cadillacs and cars that belong in the 50’s, 60’s, or even the 70’s.
However, modern technologies like cell phones and computers are used frequently in the episodes, suggesting that the show could have been set in the late 80’s or the 90’s.
What time period do you guys think "Hey Arnold" was set in?

I imagined that the show was set in the late 90s since 1998-99 is when cell phones became more accessible for regular people. Also the old cars could establish that there were a lot of older people living in the area.