Birthday Ideas for 3 Year Old

Hi, K.!
We just moved FROM Arizona to Pittsburgh. I know how you feel -- my daughter's 2nd birthday is in a few weeks and I'm feeling the same way.
I don't know which part of the state you're in, but if you're in either the Phoenix or Tucson area, the weather must still be pretty warm! Both cities have free "sprinkler parks." (I don't know about Flagstaff/up north...)
They're a lot of fun, and -- with proper supervision, of course -- totally safe for toddlers. I'm sure both your son and his friend would have a great time playing there, and you could take along a small picnic lunch, presents, balloons and a birthday cake or cupcakes.
It could be a nice, easy, low-cost way to both celebrate the occasion and to get to know your new city. Plus, there will be lots of other kids for your son to interact with -- you could even invite some of them to come over to the picnic area for cake, if you want. And the photo opportunities are excellent! Kids playing in sprinklers... what could be cuter?!?
You can look up the sprinkler park locations on either city's Parks & Rec website.
Good luck! Arizona is great -- I'm sure you'll come to love it :)

My daughter turned 3 last year and we had a few friends over for cake and ice cream and then just our family went to build a bear to make a stuffed animal. My little girl and two boys had a great time and it was a low key family birthday. She loves her Hello Kitty and remembers it was a fun day with her brothers.

Hi K.- welcome to Arizona! What are are you going to be moving to. There are many mom's groups out here that you can join to help meet more kids too. Feel free to message me if you want to get together for a playdate (my daughter will be 3 in november) and I can help introduce you to the area.

As for party ideas- if you are keeping it to just the 1 friend, the phoenix Children's museum could be fun. I am doing a Dora party for my daughter so you could maybe do a Diego theme for your son and take him and his friend on a planned out "adventure" and have them dress up as Diego and have an orange backpack filled with adventure tools. Encanto Park in Phoenix has a train ride and a whole amusement park called Enchanted Island. That is fun for a small group of people and not too expensive.

why not try having a party picnic in the local park, get some weighed down ballons and games, it might attract the attention of future friends for you both.

at 3 children do not need to know a child to have fun. short of posting a notice that you are having a party for your 3 year old look around your neighborhood and invite other kids. my kids were always able to fun friends whereever they went. as far as a theme almost any thing would do. keep it simple and possibly use the party as a icebreaker for you --- you know it as well as I that adults have a harder time finding friends.

McCormick Railroad Park, on Scottsdale and Indian Bend, is lots of fun for birthday parties. They have a great playground, 2 train rides, a carousel, a play-sized old west town, and lots of room to run around. I know you can rent ramadas, but they also have lots of picnic tables where you could set up for a smaller party.
Other places- Phoenix Zoo, Wildlife World Zoo, Imagination Avenue, AZ Science Center, Phoenix Children's Museum