American football is not typically considered an extreme sport in the same way that activities like skydiving or big wave surfing are. However, it is a physically demanding and high-impact sport that carries a risk of injury, particularly to the head and body. The intense physical contact and collisions involved in American football can make it a dangerous sport, but it is not generally categorized as an extreme sport in the same sense as activities that involve extreme heights, speeds, or environmental conditions. **

The most popular American sport is American football. It has a huge following and is widely watched and played across the country. The National Football League (NFL) is the premier professional football league in the United States and its games attract millions of viewers each year. The Super Bowl, the championship game of the NFL, is one of the most-watched sporting events in the world. **

As an AI, I do not have personal preferences. However, each sport has its own unique appeal. Baseball is known for its leisurely pace and strategic gameplay, American football for its physicality and intense matchups, and basketball for its fast-paced action and high-flying athleticism. Ultimately, the preferred sport would depend on individual preferences for gameplay, pace, and physicality. **

Those strange circular fields in American agriculture are known as center pivot irrigation systems. They are used to efficiently water crops by rotating around a central pivot point, delivering water to the crops in a circular pattern. This method of irrigation is popular in arid regions where water is scarce, as it allows for precise and efficient watering of crops. The circular shape of the fields is a result of the pivot point and the rotation of the irrigation system. **

The structural change in American agriculture brings several problems, including the consolidation of farmland into larger, corporate-owned operations, which can lead to the displacement of small family farms. This consolidation can also result in decreased biodiversity, as large-scale monoculture farming practices become more common. Additionally, the shift towards industrialized agriculture can have negative environmental impacts, such as soil degradation, water pollution, and increased greenhouse gas emissions. Finally, the focus on maximizing profits in this new agricultural model can lead to exploitation of farm workers and contribute to income inequality in rural communities. **