Is 54 minutes a legal connection at LGA for US - UA (Express to Mainline) on a US ticket/flight #s?

I can't find the rules anywhere on the new usair.com and nothing wants to book it for me.

Is 54 minutes a legal connection at LGA for US - UA (Express to Mainline) on a US ticket/flight #s?

I can't find the rules anywhere on the new usair.com and nothing wants to book it for me.

Ive had a 30 min connection at LGA from 1:04-1:34 which we would have made, but my parents totally forgot about the flt, went buying stuff the kiosks, then I go lost and was going to gate 7 but essentially found myself at the Shuttle area. Agent closed the doors way too early (at 1:22). We were going to fly LGA-PIT ERJ AWAC and PIT-ORD 170 REPUBLIC. Turned out pretty well. Parents got A320 LGA-ORD on UA, while I refused to fly UA nonstop or just UA at all and got confirmed F on LGA-CLT and CLT-ORD. Back to topic though. Yes its possible. The other thing is, I came in from BOS which is Shuttle flt so they have got to be on time.

Lga Standard Connect Time - .45
Minimum Connect Time Exceptions
Nct Ord 00040
Airlines Type Time Flights
Hp/us D/d .25
Us/hp D/d .25
Us/us D/d .25