There has been a really solid core of drivers that have run all of the pavement events so far in 2019. LORP was a little light in May due to several guys struggling with their Little 500 efforts and having to qualify on Friday. There were 21 cars at Madison, Wisconsin last month. I believe last year's Salem race had 19 entries and was a great show (you can watch last years event at LoudPedal TV for free).
I would expect 18 to 20 cars for Saturday, the weather looks great so far.