Celtic and Rangers (along with Aberdeen who joined later) have never been relegated. Heart of Midlothian and St. Mirren are still in the upper reaches of the Scottish league system although the four do not play in this league, plying their trade in the Scottish Premier League instead. Dumbarton play in the Third Division (the fourth flight) of the league. Every other club is either defunct or out of the League.
In its initial season Rangers and Dumbarton topped the league on equal points. No thought of separating teams by goal average, or goal difference had been considered and the two teams played a play-off to decide the winner. The result of the play-off was a 2:2 draw and both teams were declared joint winners, each taking possession of the trophy for six months. This was only occasion in which the Scottish league was tied. Goal average was only brought in for the 1921/22 and replaced by goal difference for the 1971/72 season.
In 1923, the League decided to introduce a Third Division. The Western Football League (in Scotland) was used as its backbone but the new set-up lasted only three years before it collapsed under heavy financial losses.
From 1926 until 1946, the League returned to two divisions. Post-World War II reforms saw the League resume with three divisions.
Postwar seasons saw the divisions renamed 'A', 'B' and 'C' with the last section also including reserve sides. In 1949, the 'C' Division was expanded to two sections - North-West and South-East.
The withdrawal of the reserves from 'C' Division in 1955 saw a return to two divisions which would last until the formation of the Premier Division in 1975.
Following the demise of Third Lanark in 1967, the Second Division kept operating with just 19 clubs; the situation would not be corrected until the next change of format.
This change of structure split the league into three divisions, Premier, First, and Second Divisions. This permitted more frequent fixtures between the top clubs; the expectation was that meant greater revenue for them, and it was hoped it would stimulate greater interest, at a time when attendance at league matches had dropped alarmingly. A new club entered the league - Meadowbank Thistle - who were Edinburgh's third league team (who would eventually become Livingston F.C. in 1995. )
This three-divisional structure (of 38 clubs) continued until 1994.
In 1998 the Premier Division clubs split from the league to form the Scottish Premier League (SPL).
The remaining leagues, of ten clubs each, kept their names and the Premier Division was not reconstituted, leaving First, Second and Third Divisions.
When the SPL expanded to 12 clubs in 2000, the SFL took in two new members in a further round of league enlargement with Elgin City and Peterhead joining from the Highland League. This brought the Scottish Leagues up to 42 teams - 12 in the Scottish Premier League and 10 in each of the three Scottish Football League divisions.
Gala Fairydean have been rejected from the Scottish League at each time of asking, despite having a setup and facilities arguably better than some of their opponents. Other teams that have fallen at this hurdle include Whitehill Welfare.
Scottish club Gretna, who had previously played in the English Northern Premier League, were admitted in 2002 to replace the defunct Airdrieonians. Shortly afterwards Airdrie United who came second in the process when Gretna were chosen to fill the gap created by Airdrieonians' demise, simply purchased ailing side Clydebank F.C., renaming then and moving them to Airdrie.
Each season the winners of the First Division are eligible to be promoted to the Scottish Premier League providing their stadium meets certain criteria. As of March 2005, these criteria include priority tenancy or ownership of a stadium with at least 6,000 seats, and an undersoil heating system for the pitch. Falkirk F.C.'s failure to meet these demands resulted in their being refused promotion despite winning the First Division in 2002/03; at that time, the SPL required 10,000 seats for its member clubs. They have since built a new stadium with an all-seater capacity of 7,000, and prompted by a campaign by Inverness Caledonian Thistle, the SPL reduced its seating requirement to 6,000, making them now eligible to join the SPL, having won the First Division again in 2004/05.
In 2008, the SFL again required a new team as a result of the demise of Gretna. Annan Athletic, previously of the East of Scotland League, were voted to join the Third Division in time for the 2008-09 season. There were 5 bids in total for the position, with unsuccessful bids coming from Spartans, Cove Rangers, Preston Athletic F.C. and Edinburgh City.
Promotion and relegation between the First and Second Division, and the Second and Third Division, are currently decided using a combination of automatic movement and playoffs.
Rangers have won the greatest number of league titles in the league's history, with 51 national championships (including SPL titles) to their name.