They get your email info to send the free tickets but that is the only information. In 2016 for theVirginia rally people came from as far as PA, MD,WVA,DC and OH. It was a late rally on a Sunday night also. It was an anti establishment surge and anti political correctness movement. The press/ media caused the Trump movement and that makes it all the sweeter.
The Democrats know that Trump is a fighter and will rally the people to his side if they try to impeach him.
The Dems have figured out that fighting Trump increases his popularity... It’s great having a President with balls.