Question - Volunteers and the US Selective Service Act 1917

[Norwester]

From Wikipedia, so not the most reliable source, but it raises a question for me which I hope someone here can answer:

 

"By the guidelines set down by the Selective Service Act, all males aged 18 to 30 were required to register to potentially be selected for military service. At the request of the War Department, Congress amended the law in August 1918 to expand the age range to include all men 18 to 45, and to bar further volunteering."

https://en.wikipedia.org/wiki/Selective_Service_Act_of_1917#Effects

 

So does this mean that no more volunteers were accepted into the US military during the war after August 1918? Were all further recruits only draftees?