The "Tri-metropolitain Country area is Multnomah County, Washington Country and Clackamas County. (the fourth unofficial county is Clark County Washington using the Douglas Adams' Rule of Trilogies, although this is more of a joke perpetuated by the fact that the majority of the residents of Clark County work in the Tri-County Metro Area) Tri Met is a combination of public transportation services for those areas. These Include:
1.) Bus service throught the metropolitain area. All busses currently operated by Tri-Met are equipped with bike racks and lifts/seating for the disabled.

2.) MAX (Metro Area Express) Light-Rail service, which is also bicycle friendly and fully accessible to the disabled.

3.) Van Service for the diabled. Lift equipped vans which will pick up qualified individuals from their homes and take them to their exact destination (my great-grandmother uses this service extensivley).

4.) Trolley Service, coming soon, old fashioned cable-cars will connect the Northwest and Southwest shopping districts.

Tri-met is one of the top rated public transportation services in the United States (in the top five) and makes life very easy for those of us who cannot afford or do not want to own a car to conduct our daily lives. The rates are reasonable, the busses run fairly frequently, and go just about every where you need to be (although the furthur you get from downtown portland the tougher this becomes). is it perfect? Of course not, but until more people use it (and vote "yes" on measures to increase funding) it's not going to be. However it's still not at all bad.