Comparison of American and Canadian football in the context of "Canadian football"

American football, referred to simply as football in the United States and Canada and also known as gridiron football, is a team sport played by two teams of eleven players on a rectangular field with goalposts at each end. The offense, the team with possession of the oval-shaped football, attempts to advance down the field by running with the ball or throwing it, while the defense, the team without possession of the ball, aims to stop the offense's advance and to take control of the ball for themselves. The offense must advance the ball at least ten yards in four downs or plays; if they fail, they turn over the football to the defense, but if they succeed, they are given a new set of four downs to continue the drive. Points are scored primarily by advancing the ball into the opposing team's end zone for a touchdown or kicking the ball through the opponent's goalposts for a field goal. The team with the most points at the end of the game wins. In the case of a tie after four quarters, the game enters overtime.

American football evolved in the United States, originating from the sports of soccer and rugby. The first American football game was played on November 6, 1869, between two college teams, Rutgers and Princeton, using rules based on the rules of soccer at the time; by 1875, the sport had adopted rules similar to rugby union. A set of rule changes drawn up from 1880 onward by Walter Camp, the "Father of American Football", established concepts that would define the sport, among them the snap, the line of scrimmage, eleven-player teams, and the concept of downs. Later rule changes legalized the forward pass, created the neutral zone, and specified the size and shape of the football. The modern sport is closely related to Canadian football, which evolved in parallel with and at the same time as the American game; the two sports are considered the primary variants of gridiron football.

A multi-purpose stadium is a type of stadium designed to be easily used for multiple types of events. While any stadium could potentially host more than one type of sport or event, this concept usually refers to a design philosophy that stresses multifunctionality over speciality. It is used most commonly in Canada and the United States, where the two most popular outdoor team sports—Canadian football or American football and baseball—require radically different facilities. Football uses a rectangular field, while baseball is played on a diamond with a large outfield. Since Canadian football fields are larger than American ones, the design specifications for Canadian facilities are somewhat less demanding. The particular design to accommodate both is usually an oval, although some later designs use an octorad. While building stadiums in this manner allows sports teams and governments to share costs, it also presents some challenges.

In North America, multipurpose stadiums were primarily built during the 1960s and 1970s as shared home stadiums for Major League Baseball and National Football League or Canadian Football League teams. Some stadiums were renovated to allow multipurpose configurations during the 1980s. This type of stadium is associated with an era of suburbanization, in which many sports teams followed their fans out of large cities into areas with cheaper, more plentiful land. They were usually built near highways and had large parking lots, but were rarely connected to public transit. As multipurpose stadiums were rarely ideal for both sports usually housed in them, they had fallen out of favor by the 1990s, with the SkyDome (in Canada) that opened in 1989 being the last such stadium completed to accommodate baseball and football. With the completion of the Truman Sports Complex in Kansas City in 1973, a model for purpose-built stadiums was laid down. Since the Baltimore Orioles left the multi-purpose Memorial Stadium for the baseball-only Oriole Park at Camden Yards in 1992, most major league sports stadiums have been built specifically for one sport. However, some newer NFL stadiums (e.g. Seattle, Atlanta, Charlotte) have been built with consideration for the possible use of the stadium for Major League Soccer or international soccer, which has similar field dimensions to American football. Fields that are suitable for soccer are almost always equally suitable for either rugby code (rugby union or rugby league), and the 2031 Men's Rugby World Cup is expected to employ the same stadiums as the NFL and MLS.