A local 1917 item about robberies at the park suggests that it was open that year. The article also mentions thefts of electrical transmission wire in its vicinity.
A 1918 item describes soldiers bivouacking at the (apparently closed) park -- they brought in a field generator to provide electrical power.
An October, 1920, newspaper item (on authorization to buy the carousel and move it to
Pullen Park) notes "The scenic railway at Bloomsbury Park is still there though the amusement place has been abandoned for about three years."