There were 17 exhibitors at the first show in 1907. How many cars were on exhibit I cannot determine.
Well here in Detroit the 2012 auto show was the biggest yet.
The Car Coach - 2011 2011 Detroit Auto Show was released on: USA: 13 January 2011
Cars.TV - 2009 Detroit Auto Show 3 - 7.4 was released on: USA: 12 October 2009
No
Motorweek - 1987 Detroit Auto Show Special 25-21 was released on: USA: 27 January 2006
The best auto shows that have the best concept cars are ones run by the companies themselves like the New York Auto Show at the Jacob Javits Center.
The Car Coach - 2011 Dream Cars at the New York Auto Show was released on: USA: 9 May 2013
Cars-TV - 2009 Los Angeles Auto Show 10-17 was released on: USA: 17 March 2013
Cars-TV - 2009 Los Angeles Auto Show 9-5 was released on: USA: 24 October 2011
Cars-TV - 2009 L-A- Auto Show 3 7-21 was released on: USA: 10 May 2010
There are multiple auto finder websites. One of the most popular is autotrader. They show cars for sale in many different areas in the country as well as prices.
They were pre-production Show cars destined for the auto show- but went down with the old Tub. One was supposed to be an Isetta.