We are trying to work out an electoral slogan for a party. Which ones are correct or the best: in every street, in every season or on every street, on every season?
The answer to this might be different depending on whether you are using American English or British English. In British English, the first of the two slogans would clearly be the best. In American English, however, a mix of the two would be best. If these two slogans are your only choices, definitely use the first one.
There is no preposition that is clearly better than the other for use with the word “street.” It really depends on how you think of the street. In American English, we apparently think of the street as the physical surface of the ground. Therefore, we tend to say things like “the store is on X Street.” By contrast, the British seem to think of the street more as a district or as a three-dimensional area. Therefore, they will say that the store is “in Street X.” However, the British way of saying this is familiar enough to many Americans that a slogan using “In every street” would only sound a little odd, not completely wrong.
Even so, you really cannot use the second slogan. I have never heard or read the preposition “on” being used to refer to a season of the year. Both Americans and British, to my knowledge, invariably say that things happen “in the summer” or “in summer.” For example, in this article from a British newspaper regarding the World Cup finals for 2022, we are told that they expect “that the World Cup would not be played in the summer” because it is too hot in Qatar in the summer. This means that the second slogan would sound wrong in either British English or American English.
In American English, then, the most likely slogan would be “on every street, in every season.” This would sound most natural and most appealing. The slogan “in every street, in every season” would be proper in British English but would sound somewhat foreign to American ears. In either case, do not use the second slogan.