A couple of observations. You can really tell a lot about a person with careful examination of their collection.
1) Many of us have started collecting and then stopped for a wide variety of reasons. Looking at this collection you can see the rise, peak and decline of my co-workers childhood interest in collecting baseball cards. The left-most column contains cards from the 60's with the bulk of the row containing cards from 1969 as depicted by a relatively nice Tom Seaver card. Moving left to right their is an entire row for 1970 and 1971. The fourth row is comprised of 1972 and 1973 with the '72's accounting for 2/3rds of it. The final row is primarily dominated by 1974's and some 1975's. The back most part of the last row contains the equivalent of a pack from each year 1976-1979. Clearly in looking at this box you can see the peak of interest was 1970-1972. Being 8 years my senior he would have been 8 to 10 years old which makes perfect sense.
2) Favorite team. Much like a favorite stuffed animal that is figuratively, "loved to death" with missing eyes, matted fur, and stains, similar signs exist on baseball cards of a child's favorite team. In this case both Chicago teams are well loved with a preference towards the Cubs in particular as clearly seen by the pinholes, paper tears (from being taped to something- wall, locker, notebook, door?) creases and corner wear from being shoved into ones pockets.
3) Even back in the 60's kids hated getting cards of players in last year's uniforms. The number of cards I found with the team name crossed out and replaced with Cubs or White Sox is comical.
4) Checklists served a legitimate purpose. Highly coveted, they were the only way to make sure you had card of your entire team. It's not like you could go to Topps website and print out the checklist. Most of the ones you find from that era, and this collection is no exception, are well marked. That is why clean, unchecked samples command good money as they are numbered as part of the set itself.
I'll show scans of some of the other key cards found in a later post but also in a top loader in the above picture is a 1970 Thurman Munson RC, I also found (1) more '69 Reggie Jackson RC, lots of good condition cards of Pete Rose including 1970,71,72,73, and 74, a nice 1975 Robin Yount RC, a '69 Nolan Ryan and more goodies.
Now onto sorting cards from the other 3 sports. :)