Both Allen and McKinney declined to join DART, so the light-rail stopped in Plano.
Now, all of the people in Allen and McKinney drive to the park & ride station in Plano and take the train. The parking lot was expanded TWICE, and it still filled up by 7:00 AM.
The complaints got so bad that DART finally instituted a fee for parking. Anyone that lived in a city that pays DART taxes (1% sales tax rider) can get a parking sticker that exempts them from the fee.
The fee plan wasn't economically viable, so they had to abandon it. Plan B was to reserve the north lot (the old lumberyard property) for permit holders from DART system cities, and allow anyone to park for free in the south and the west lots. There are always a few empty spaces for Plano folks traveling in after rush hour at the far end of the north lots.