I live in Gilbert wich is kind of a suburb of Phoenix/Tempe/Mesa in the east valley which is an awesome place to live man. From my house I can be at ET Motopark in about 20 min. The have 4 tracks PW, 80, Vet and Pro. This is a nice facility and big enough so that the tracks don't usually get too busy on practice day. (etmotopark.c*m)
To the south about 30-40min away, near a little boom town in the middle of the desert called Casa Grande, lies Moto Grande. This track is real technical and tight with big pit jumps and it is just an awesome layout. Remember this place in the summer time because they have night practice. Believe me, in the summer it gets up to around 115 degrees during the day. You don't want to be out there in the desert in those conditions unless you really like your nutz roasted. Don't under estimate the deadliness of the desert either. Every summer, you almost can't go one day without hearing about how some hiker had to get air lifted because he just took off into the mountains with no water or something. And right after that news bit you'll hear about a drowning death. Go figure, it's a crazy world we live in. You can avoid trouble by making sure you stay (as) cool (as you can) and keep hydrated. One good thing is I never hear of riders having these troubles, it's always the hikers.
On the west side of the valley there's Speedworld (speedworldmxpark.c*m) I stopped going to this track because it is so far from the east side and there's quality riding now where I live so less drive time = more ride time. Speedworld is a sweet track none-the-less and before ET and Moto G got all dialed in that was where we went every weekend.
To the north there's Canyon. I can't find a website for them but I'm sure if you live in Cave Creek or north to northwest Phoenix you will seek out this landmark track which is a staple of the valley motocross community and has been for many years.
There are other tracks like AZ Cycle Park and Cottonwood. There's acres and acres of BLM land for single track, free riding and honing your desert riding skills. A few hours to the north there's pines and forest either, Payson, Flagstaff (snowboarding too), Pinetop (snowboarding too) if you want to ride forest trails and stuff.
Then a few hours to the west, just across the AZ/CA border (near Yuma) is Glamis. Sand, sand everywhere my friend and it is a hell of a lot of fun to visit. If you have never been I strongly suggest you go at least once. It's like riding on another planet created by the dirtbike Gods.
One thing however is that the riding space there is slowly being taken out of service by the Communist Land Grab effort. They are using this weed to justify the closure of state land. You see, the Sierra Club and it's cohorts believe that this weed that grows there sometimes has more rights than you do and they are trying to close one of the most unique and awesome places in the North American to ride.
Wherever you live, please support the American Sand Association and save our dunes. Visit their website for more than enough info about the fight. They are doing an excellent job standing up for people who ride so please support their effort. (americansandassociation.*rg)
Hope that helps!
'05 CRF450 #242