American and Canadian football are gridiron codes of football that are very similar; both have their origins partly in rugby football, but some key differences exist between the two codes.
History
Rugby football was introduced to North America in Canada by the British Army garrison in Montreal, which played a series of games with McGill University. In 1874, the United States' Harvard University hosted Canada's McGill University to play the new game derived from rugby football in a home-and-home series.
When the Canadians arrived several days early, to take advantage of the trip to see Boston and the surrounding areas, they held daily practices. During this time, the Americans were surprised to see the Canadians kick, chase, and then run with the ball. Picking up and running with the ball violated a basic rule of the American game of the day; when the U.S. captain (Henry Grant) pointed this out to the captain of the Canadian team (David Roger), the reply was simple: Running with the ball is a core part of the Canadian game. When the American asked which game the Canadians played, David replied "rugby". After some negotiation, they decided to play a game with half and half Canadian/U.S. rules. Thus, many of the similarities and differences between the Canadian and American games indeed came out of this original series where each home team set the rules. For instance, Harvard, because of a lack of campus space, did not have a full-sized rugby pitch. Their pitch was only long by wide (slightly less than the -yard width of the current regulation-sized field for American football).
Because of the reduced field, the Harvard team opted for 11 players per side, four fewer than the regulation 15 of rugby union. To generate more offense, Harvard also increased the number of downs from three, as set by McGill, to four. Furthermore, the Harvard players so enjoyed running with the ball, this rule was wholly adopted into all Harvard play following the two games with McGill. While the American team bested the Canadian (3–0 and a following tie game), both countries' flavours of football were forever changed and linked to one another. Both the Canadian and American games still have some things in common with the two varieties of rugby, especially rugby league, and because of the similarities, the National Football League (NFL) had a formal relationship with the Canadian Football League (CFL) between 1997 and 2008.
Many, if perhaps not most, of the rules differences have arisen because of rules changes in American football in the early 20th century, which have not been copied by Canadian football. The major Canadian codes never abolished the onside scrimmage kick (see Kicker advancing the ball below) or restricted backfield motion, while the American college football (from whose code all American codes derive) did. Canadian football was late in adopting the hand snap and the forward pass, although one would not suspect the latter from play today. Additionally, Canadian football was slower in removing restrictions on blocking, but caught up by the 1970s so that no significant differences remain today. Similarly, differences in scoring (the Canadian game valuing touchdowns less) opened up from the late 19th century, but were erased by the 1950s. An area in which American football has been more conservative is the retention of the fair catch (see below). The American game's modern rules were developed by Walter Camp in the late 19th and early 20th centuries, whereas the modern Canadian game was devised by John Thrift Meldrum Burnside, whose Burnside rules, invented around the same time, were developed independently from Camp's rules.
In some regions along the Canada-U.S. border, especially western areas, some high schools from opposite sides of the border regularly play games against one another (typically one or two per team per season). By agreement between the governing bodies involved, the field of the home team is considered a legal field, although it is a different size from one school's normal field. In all but a few cases, the rules of the home team are followed throughout the game.
Many CFL players are Americans who grew up playing American football and cannot find a place in the NFL, or who prefer to play in the CFL; strict import quotas restrict the number of non-Canadian players. Furthermore, the classifications of import (non-Canadian) and non-import (Canadian) were highly restrictive and required a player to have been in Canada since childhood to qualify as a nonimport (i.e. a player cannot simply become a Canadian citizen and become a nonimport, nor can he arrive in Canada during high school or college; both scenarios would still have the player in question classified as an import and counted against the team's maximum); these restrictions were loosened beginning in 2014 so that anyone who had become a Canadian citizen at any time before signing with the league for the first time could qualify as a nonimport player. For individuals who played both American and Canadian football professionally, their career statistic totals are considered to be their combined totals from their careers in both the CFL and NFL. Warren Moon, for example, was the all-time professional football leader in passing yards after an illustrious career in both leagues. He was surpassed in 2006 by Damon Allen, who in turn was surpassed by Anthony Calvillo in 2011, both of whose careers were exclusively in the CFL, then Calvillo was surpassed by Drew Brees and Tom Brady, both of whom played their entire careers in the NFL.
Differences Several important specific differences exist between the Canadian and American versions of the game of football:
Playing area
The official playing field in Canadian football is larger than the American, and similar to American fields before 1912. The Canadian field of play is , compared to in American football. Beginning in 2027, the playing field in the CFL will be shortened to 100 yards.
From 1986, Canadian end zones are deep: beginning in 2027, the end zone in the CFL will be shortened to 15 yards. The American end zones are deep.
Canadian end zones were previously , with Vancouver's BC Place the first to use the 20-yard-long end zone in 1983, and since 2016, the home of the CFL's Toronto Argonauts, BMO Field, has used an end zone. Including the end zones, the American field is about 34% smaller than the Canadian field ( for the Canadian field vs for the American field) - this will be reduced to about 24% smaller from 2027, with the Canadian field being reduced to - but the Canadian field occasionally has its end zone truncated at the corners so that the field fits in the infield of a running track. Once a fairly common practice, the only example in the CFL is the Percival Molson Memorial Stadium, home of the Montreal Alouettes. In contrast, the smaller American regulation field easily fits within a running track, although today such dual use of facilities is only common for high school football and the lower levels of college football.
The most recent example of an NFL team using a stadium also used for track and field was the Los Angeles Rams, who played at Los Angeles Memorial Coliseum after returning to the Los Angeles metropolitan area while SoFi Stadium was being built.
The goalposts for kicking are placed at the goal line in Canadian football, but at the end line in the American game professionally since 1974 (the college game has had them at the end line since 1927). Beginning in 2027, the goal posts in the CFL will be placed at the end line, similar to American football. In Canadian rules, the distance between the sideline and hash marks is ; in 2022, the CFL narrowed the hash mark spacing to .; In American amateur rules, at the high school level, the distance is , sectioning the field into three almost equal columns. The hash marks are closer together at the American college level, where they are from the sideline, and in the NFL, where they are from the sideline and the distance between them is the same as that between the goalposts.
Because of the larger field, many American football venues are generally unfit for the Canadian game. While several American stadia could accommodate the extra feet () per side in width (multipurpose stadia, baseball parks converted for football, and some soccer-specific stadiums are particularly good fits), most American stadia would lose between 15 and 18 rows of seating in each end zone because the field is longer on each end - in many smaller venues, this would be the entire end zone section, thus losing seating for at least 3,000 spectators. With the Canadian field being shortened from 2027, the field will become only longer on each end.
During the CFL's failed expansion to U.S. cities in the early 1990s, Canadian football was either played on fields designed to accommodate both American football and baseball (such as the Baltimore Stallions playing at Memorial Stadium), or in some cases, on a field designed for American football (for instance, the Memphis Mad Dogs and the Birmingham Barracudas of the CFL, playing in the Liberty Bowl and at Legion Field, respectively, played the Canadian game on modified American-sized fields because of the inability of the stadia to adapt to the larger field). The Alamodome, originally built as a multipurpose dome, proved to best accommodate both Canadian football (the CFL's San Antonio Texans) and American football (Alamo Bowl, Dallas Cowboys training camp, the New Orleans Saints after Hurricane Katrina, the NFLPA Game, the U.S. Army All-American Bowl, and the UTSA Roadrunners), although Canadian football is no longer played there. Similarly, Hornet Stadium fairly easily adapted to both the Canadian and American games, as it was built with a running track in which the Canadian field fits with only some cuts to the corners. Hornet Stadium hosts California State University, Sacramento (more often known as Sacramento State), hosted the Sacramento Surge and Sacramento Mountain Lions in American football and the Sacramento Gold Miners in Canadian football.
Team size
American teams use 11 players, while Canadian teams have 12 players on the field per side. Both games have the same number of offensive players required at the line of scrimmage, so the 12th player in the Canadian game plays a backfield position on offence, whereas this is usually a defensive back on defence.
Because of this, position designations of the various offensive and defensive lines vary. For example, most formations in Canadian football have no tight ends, these having been phased out in 1980. The typical offensive arrangement in Canadian football is three slotbacks instead of the American tight end and fullback while on the defensive end of the ball, two defensive halfbacks are used instead of one strong safety in the American game.
The ball
The sizes of individual American and Canadian footballs can vary within specified size limitations. Despite the CFL and NFL having different specifications until 2018, they overlapped to a sufficient degree that from at least 1985 forward, the same ball could fall within the requirements of both leagues.
Historically the CFL ball was slightly larger, both because of slightly bigger specifications, but also because CFL manufacturers tended to make balls at the larger end of the allowed tolerances as opposed to NFL manufacturers, which built balls to the smaller end. However, the CFL has updated its specifications twice—first in 1985, and most recently in 2018. The latter change saw the league adopt the NFL's specifications.
Before it adopted NFL standards, the CFL's regulation football size was specified as short circumference from ; long circumference from .
The regulation size for an NFL football is specified as short circumference from ; long circumference from .