Can't single out to one city. Pick any city on the Hawaiian Coastlines and lower altitude locations, and you have a perpetual growing season. If keeping to a continental U.S. analysis, a few locations might be candidates: Key West, Fl; Coronado, CA; Yuma, AZ; San Francisco, CA (farthest north);
Montana....
The growing season is the same as in the United States. The growing season in Switzerland is five months long.
Regions near the equator typically have the longest growing seasons due to their consistent warmth and ample sunlight year-round. This includes areas in countries like Ecuador, Indonesia, and parts of Africa.
southern states
Watermelon grow best in warmer climates that have above average rainfall. The southern states in the United States are good for growing watermelons. They will also grow in northern states if planted early enough to allow for a good growing season.
The longest river in the United States is the Mississippi River.
Corn can be grown in every US state except Alaska, due to its climate and short growing season.
The longest mountain range in the United States is the Rocky Mountains.
The longest river in the United States is the Mississippi River.
Seasonal fruits mean what ever is growing fresh right now. So strawberries are in season in the United States in June.
Cotton requires a longer growing season and hotter weather than is present in the North - it doesn't do well if the temperature drops below 60 °F (~15 °C) and thrives in temperatures around 90 °F (~32 °C). Cotton simply will not thrive in the the colder temperatures present most of the year in the North. It also requires a fairly long growing season - again, a problem in the North. Most cotton growing regions fit the description of hot and fairly long growing season - Southeastern US, Egypt, India, etc.
Yes, the southeast region of the United States generally has a longer growing season compared to other parts of the country. This is due to its milder winters and typically longer periods of warm weather, which can extend the planting and harvesting seasons for many crops.