[drawkbox]

Amtrak already does some screening and they increased their security like all others did from rental cars to busses to trains to planes. However the nature of flying has a much higher reach in terms of potential damage which was realized on 9/11 really.

Trains are less of a threat. Attackers can only really cause damage on a train to a section and maybe a derailment.

Plane terrorism is broader. With a plane everyone is at risk and the plane could be used to attack other things.

Train terrorism is limited. A train can't be taken off course. A train can't be all blown up. Even a massive derailment only affects a section. An attack would be a tragedy but it has rails so to speak on the reach of the damage. Maybe if they blew it up over a bridge or by a building in a city it could cause more damage or some other trigger like causing another disaster. You to have the threat of people setting explosives on the track. There was one of those in 1995 in Arizona where 1 died and 78 were injured, supposedly the attackers were avenging the Waco Siege. [1] Looks like that is the only terrorism event on trains in the US. [2] Subways and metros are probably more targeted in the city.

[1] https://en.wikipedia.org/wiki/1995_Palo_Verde,_Arizona_derai...

[2] https://en.wikipedia.org/wiki/List_of_terrorist_incidents_in...