What streets are considered the boundaries for St. Nicholas?
Good question. It depends on the map and who you ask. On Google Maps (https://www.google.com/maps/place/St.+Nicholas,+Jacksonville,+FL+32207/@30.3054708,-81.6420888,14z/data=!3m1!4b1!4m5!3m4!1s0x88e5b6601d07bbdd:0x6742761d0231f838!8m2!3d30.3086189!4d-81.6350478), it's bounded by Holmesdale Road to the West, the St. Johns over to Millers Creek, then Atlantic Blvd to the Hart Bridge Expressway. On the south end, it's Beach Boulevard over to about the Hart Bridge Expressway.
But when I used to live on Old Hickory Road, that whole area up there and Bishop Kenney was also considered St. Nicholas. Also, when I lived on Larchmont Road, everyone considered it to be St. Nicholas rather than Spring Park. Certainly the strip of businesses south of Beach Boulevard are part of the St. Nicholas Town Center. In general there's a lot of overlap with Spring Park; St. Nicholas Playground is south of Spring Park Elementary.