Here it is. Trying to piece together the timeline made my head heart, but here we go:

"Love, and the Television Set" is what I originally thought took place during 1951-53, though I have narrowed it down to be '52.

Season 1 takes place during the year 1955 (Richie is stated to be 17 in episode 2, "The Lemon").

Most of season 2 takes place during the end of '55 ("Haunted" takes place during Halloween of '55, and "Guess Who's Coming To Christmas" takes place during Christmas of '55). Also in the season 2 episode "Who's Sorry Now?", the events of "Love, and the Television Set" are stated to have happened three years ago, so the years of '52 and '55 are correct). The end of season 2 takes place during the first few months of 1956.

Sometime after Christmas of '56, Howard and Marion disown their first born son Chuck, because his grades were so bad he got kicked out of college.
The season 2 episode, "Not The Making Of The President" takes place during US presidential election 1956 (Eisenhower vs Stevenson)

Richie is still 17 in season 3, meaning a but considered 18 around the end of season 3, meaning it's around 1957-1958.

That was the end of pure guessing, as seasons 4-11 have more clues to what time period they take place in.

Richie, Potsie, and Ralph were in Jefferson High's graduating class of 1960, so season 4 begins in 1959 at the earliest, and 1960 at the latest.

Season 5 begins in the summer of 1960.

Season 6's "Christmas Time" takes place in 1961 (as noted on the family photograph), so seasons 5-6 take place in '61.

In season 7, Joanie is a senior. Richie and Ralph were drafted to the U.S. army sometime in mid 1962.

Season 8 takes place throughout mid 1961 and ends shortly before the summer of '62.

Season 9 begins in the summer of 1962, and probably ends sometime during the end of '62 or beginning of '63.

Just like the kids in American Graffiti, Joanie and Chachi were in the graduating class of '62.

Season 10 takes place throughout '63 and '64 ("Joanie Loves Chachi", which takes place during season 10 of Happy Days, is known to take place during the early-mid 60s).

In season 11's "Passages", Joanie and a few others are wearing shirts for The Kink's 1965 world tour, meaning the final season takes place in 1965 at the earliest.

There. The Happy Days timeline finally solved. Any thoughts?

A lot of research and thought went into this. Thank you for your efforts

No problem, just trying to help out my fellow fans solve the headache that is the Happy Days timeline.

SuperMarioNic said:

"Most of season 2 takes place during the end of '58 ("Haunted" takes place during Halloween of '58, and "Guess Who's Coming To Christmas" takes place during Christmas of '58). Also in the season 2 episode "Who's Sorry Now?", the events of "Love, and the Television Set" are stated to have happened three years ago, so the years of '55 and '58 are correct). The end of season 2 takes place during the first few months of 1959".

How do you get around Season 2 episode 15 "The Not Making of a President", that episode takes place during the 1956 Presidential Campaign.

The 1956 presidential election between Stevenson and Ike.

See, that's where we go wrong. See, "The Not Making Of A President" DOES take place in '56, meaning season 1 and the first half of 2 take place in '55.

I heard somewhere decades ago that the first season was supposed to be 1954, but that makes no sense to me. We're hearing songs like All Shook Up and other rock and roll favorites from 56 and beyond. Chuck Berry comes to town for a show; his first hit was in 1955.

Here it is. Trying to piece together the timeline made my head heart, but here we go:

"Love, and the Television Set" is what I originally thought took place during 1951-53, but based off of later evidence, it takes place either at the tail end of 1954 or beginning of '55 (Richie states himself that he is 16 in the episode, being his first line in the entire pilot).

Season 1 takes place during the middle of 1958 (Richie is stated to be 17 in episode 2, "The Lemon").

Most of season 2 takes place during the end of '58 ("Haunted" takes place during Halloween of '58, and "Guess Who's Coming To Christmas" takes place during Christmas of '58). Also in the season 2 episode "Who's Sorry Now?", the events of "Love, and the Television Set" are stated to have happened three years ago, so the years of '55 and '58 are correct). The end of season 2 takes place during the first few months of 1959.

Sometime after Christmas of '58, Howard and Marion disown their first born son Chuck, because his grades were so bad he got kicked out of college.

Richie is still 17 in season 3, meaning a little less than a year has passed.

That was the end of pure guessing, as seasons 4-11 have more clues to what time period they take place in.

Richie, Potsie, and Ralph were in Jefferson High's graduating class of 1960, so season 4 begins in 1959 at the earliest, and 1960 at the latest.

Season 5 begins in the summer of 1960.

Season 6's "Christmas Time" takes place in 1961 (as noted on the family photograph), so seasons 5-6 take place in '61.

In season 7, Joanie is a senior. Richie and Ralph were drafted to the U.S. army sometime in mid 1962.

Season 8 takes place throughout mid 1961 and ends shortly before the summer of '62.

Season 9 begins in the summer of 1962, and probably ends sometime during the end of '62 or beginning of '63.

Just like the kids in American Graffiti, Joanie and Chachi were in the graduating class of '62.

Season 10 takes place throughout '63 and '64 ("Joanie Loves Chachi", which takes place during season 10 of Happy Days, is known to take place during the early-mid 60s).

In season 11's "Passages", Joanie and a few others are wearing shirts for The Kink's 1965 world tour, meaning the final season takes place in 1965 at the earliest.

There. The Happy Days timeline finally solved. Any thoughts?

This is well thought out and your rationale about Chuck being disowned is brilliant.

In season 7, when Arnold's is suffering from lack of business, Potsie remarks they should get President Kennedy to come down to Arnolds and dance with the girls, so it's definitely 1961.

It's nice to see a well-thought out post.

So that would mean that Joanie's only two years younger than Richie. I always thought she was at least four years younger. �� ����*♀️