TV schedules and listings will help determine what shows were broadcast in what year(s). Listings and schedules might also give you details such as whether a show was broadcast in color or black-and-white, whether it was a first run or a repeat episode, and language details such as closed-captioning.
Keep in mind that the number of television networks and corresponding options has increased dramatically in the last 50 years. Don't be surprised when early schedule grids and listings show only a small number of available viewing options.
TV Guide magazine is "the" source for referencing what aired on television in a given year. The national magazine was typically published on a weekly basis with occasional double issues. Past issues are not easily found online, though there are a couple of options:
epguides.com | Past Grids by Year. Fall 1970 - Fall 2011. Select a year of interest to display grids listing what aired in the fall of that year. These grids will easily indicate what day of the week a show aired, as well as its typical time slot. Grids default to airings in the central time zone.
epguides.com | Chronological List by Year. 1946 - 2020. Chronological lists of which shows aired in a given year.
Daytime TV Schedule Archive. 1947 - present. Listings of daytime television across the three major broadcast networks (ABC, CBS, and NBC). Grids are a little more nebulous than with the epguides site (above), as they do not easily indicate time zone referenced.
TV.com. If you're not familiar with a show's content, TV.com gives you a summary of the show, cast and crew (including guest stars), lists of episodes with original air dates, and episode summaries.
Yes. There are a variety of streaming sites that offer free access to "classic" television shows and commercials. Perhaps not surprisingly, free viewing options also usually contain ads.
Options include (in alphabetical order):
* Sites have expanded episode access with premium account membership.