We are traveling via bus from Aguas Calientes(possible?) to Puno, staying a night, and hoping to move directly on to La Paz, bypassing Copacabana? Are there buses from Puno to La Paz, and are they reliable and safe? I have heard (unreliably) there is some trouble and danger crossing the border. Thanks for your help. Laurel

You will need to go from Aguas Calientes to Cusco, before changing for a direct bus to Puno. Puno to La Paz is safe and relatively easy, there is no danger in crossing the border at all. Enjoy!

If you want to skip Copacabana and go directly to La Paz, then use the Desaguadero border crossing. There are international buses traveling between Puno and La Paz, and it's also to easily do the trip in 2 leg: Puno/Desaguadero and then Desaguadero/La Paz. The 1st bus will drop you off at the bridge between the 2 countries ( the smallest and most unimpressive international bridge you'll probably ever see), you get your exit stamp for Peru, walk across the bridge, get your Bolivian entrance stamp, and then walk about a block to the departure point for the minibus to La Paz.
The only problem I can see with this and the other main Peru/Bolivia border crossing by the lake is that Peru and Bolivia both have fairly frequent strikes that involve highway blockages that disrupt bus travel. Most often they only last 24 hours, but they can be annoying if you really want to get somewhere and there's no other paved route. The bus company employees usually have the most up-to-date information and will cancel or reroute their regular services if they expect problems.
I'd only change the most minimal amount of money in Desaguadero as it's all done by private individuals and the rates they offer are poor. I've heard that you get better rates on the Peruvian side, but have no personal experience with changing money on that side. The minibus ride from Desaguadero costs around Bs 8, and passes by Tiahuanaco enroute to La Paz. Try to time your travel to arrive in La Paz before dark as the minibus will drop you at the bus station/ parking lot at the top of the canyon and it's a rather dodgy place even during daylight hours. The good news is that you can easily get a minibus to take you down into the canyon where the main drag of La Paz runs. If you don't know exactly where you're going, just ask for Iglesia San Francisco, because it's fairly close to most of the backpacker hostels.

See the post in the Bolivia forum. The post was orginally on La Paz to Cuzco, however it changed from La Paz to Puno. Ivan gave very specific info, that I imagine would apply to going from Puno to La Paz albeit at a different time.
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