Hattie Sherwood Park is just west of the city of Green Lake and has been a popular swimming destination for generations.
This postcard is postmarked August 9th, 1945 from Green Lake.
Mrs. W. W. S. Carpenter
210 S. Elmwood Ave
Oak Park, Ill
Text (sadly cut off by my cheapo scanner)
Dear Grandma -
I'm sorry that I forgot to write you all the time. We had fun on the mail boat ride yesterday. Will write tomorrow.
(Thankfully the old Victorian home still stands at 210 S Elmwood. According to Google Streetview anyway)