What year baseball cards are worth money is a reasonable question with an approximate answer, because the year is a proxy for how many were printed and how many survived. It sorts a box quickly and it decides nothing on its own: within every decade there are common cards and scarce ones.
Before the 1970s
Small print runs by later standards, and cards that were played with rather than stored. Survivors are relatively few and mostly worn, so condition swings prices hard and sharp examples are genuinely scarce. This is where most of the hobby's famous prices live, and it is the part of a box worth checking card by card.
The 1970s
Production rising but still modest, and collecting becoming organised toward the end of the decade. Plenty of common cards, and rookie cards of players who went on to matter are worth identifying. Condition is still doing a lot of the work at this age.
The late 1980s to the mid 1990s
The overproduced years. Enormous runs met a collecting public that stored everything carefully, which is the combination that keeps a card cheap indefinitely: high supply and good condition. Base cards from this period are generally worth what postage costs, whoever is on them. The inserts are the exception and are worth pulling out.
After the 1990s
Production of base cards remains high and the value moved into scarcity by design: serial-numbered parallels, manufacturer autographs and short prints. So for modern cards the year tells you very little and the card's own markings tell you everything. Read the card rather than the date.
Questions people ask about what year baseball cards are worth money
Is there a single best year?
No. Every decade contains both common and scarce cards, and the year is a filter for where to start rather than a verdict.
Why are early 1990s cards so cheap?
Because so many were made and so many survive in good condition. Both halves of that matter.
Are 2000s cards worth anything?
The base cards usually not; the numbered and autographed issues often. The card states which it is.
How do I use this on a mixed box?
Pull everything pre-1980, then everything that is not a base card from any year, then check those two piles.