The city of La Paz has local bus transportation, but if the weather is not too hot, most of it is walkable. However, many expats rely on their own automobiles.
There are busses and small vans (called colectivos or peseros) that run about 50 cents per ride. They are not numbered, so you need to have a basic idea of the city’s layout and/or speak enough Spanish to find out if you are boarding the correct vehicle.
Be aware that although there are plenty of taxis, they do not use meters, so you have to negotiate a price. Uber has recently started operating in the city.
There are several intercity bus terminals in La Paz, including one at the Malecón in front of the Whale Museum where busses leave for Los Cabos via Todos Santos. The fare is about US$10-$15 for the two and a half hour trip. You can also take a bus to the beaches of Pichilingüe, Balandra and Tecolote for US$2.50. They leave every hour between 9 a.m. and to 6 p.m. If you want to head north to Tijuana, it will cost your about US$100 and take 25 hours. Aguila, ABC and EcoBaja are bus companies that have their own terminals in the city. You can check schedules and prices and make reservations through them at this website.
The La Paz airport is about 10 miles southeast of the city with flights to Mexico City, Guadalajara, Tijuana, Los Angeles and Dallas, among others. However, many people prefer to use the Los Cabos airport, which has many more flights.
There also is a car ferry that connects La Paz with Topolobambo near Los Mochis, Sinaloa. The ferry takes anywhere from 8-to-18 hours to cross the Sea of Cortez, but you can take your car with you. They do not run every day, so check this website for the most recent schedule.