Vintage Trials events in the US?


After reading the superb article on trials events by the Vintage Sports-Car Club in the UK last year, I was inspired to buy a 1929 Model A for my 15-year son and myself to play with in the mud. However, I can’t seem to find any such activities here in Michigan or elsewhere in the Midwest. Are there any groups stateside that also take their prewar cars out on muddy hill climbs, bouncing and spinning through the wilds?