Database

[{"date":"2020-01-01T00:00:00.000+00:00","population":110,"state":"NY","start":"2020-01-01T00:00:00.000+00:00","end":"2021-05-26T00:00:00.000+00:00"},{"date":"2020-01-02T00:00:00.000+00:00","population":112,"state":"NY","start":"2020-01-01T00:00:00.000+00:00","end":"2021-05-26T00:00:00.000+00:00"},{"date":"2020-03-15T00:00:00.000+00:00","population":119,"state":"NY","start":"2020-01-01T00:00:00.000+00:00","end":"2021-05-26T00:00:00.000+00:00"},{"date":"2020-03-16T00:00:00.000+00:00","population":131,"state":"NY","start":"2020-01-01T00:00:00.000+00:00","end":"2021-05-26T00:00:00.000+00:00"},{"date":"2020-03-17T00:00:00.000+00:00","population":138,"state":"NY","start":"2020-01-01T00:00:00.000+00:00","end":"2021-05-26T00:00:00.000+00:00"},{"date":"2020-03-16T00:00:00.000+00:00","population":31,"state":"AL","start":"2020-03-16T00:00:00.000+00:00","end":"2021-05-24T00:00:00.000+00:00"},{"date":"2020-03-17T00:00:00.000+00:00","population":31,"state":"AL","start":"2020-03-16T00:00:00.000+00:00","end":"2021-05-24T00:00:00.000+00:00"},]

Query

db.collection.aggregate([{"$match":{$expr:{$and:[{$gt:["$date","2020-03-15"]},{$lt:["$date","2021-05-24"]}]}}},{"$group":{"_id":"$date","setSize":{"$sum":1},"set":{$push:"$state"},population:{$sum:"$population"}}}])

Result