The most direct reported figure I found is at least 45,000 people for the kickoff rally at the Great American State Fair, according to Trump’s own claim; that number has not been independently verified.

Crowd size context

Other reporting suggests the fair’s opening-day attendance was much smaller than that claim and described the event as sparsely attended.

A fuller picture is that the fair is a 16-day event, so attendance can vary a lot by day; one report says organizers expected the fair could draw 500,000 to 750,000 visitors on a typical day , with close to 2 million possible on July 4 alone.

Practical takeaway

If you need one number for a post or caption, use “at least 45,000, according to Trump” and note that independent reporting has questioned that estimate.

TL;DR: The headline figure being quoted is 45,000 , but it is a self- reported estimate rather than a verified attendance count.