Posadas is a city in Argentina.
In summer time, the heat (or better: sun) in combination with the high humidity can get increadlbly hot/strong in this region. Don't forget to take sufficient water, ice, sunblockers and clothes to protect yourself from the rays, especially if you've got sensible skin. It's a fine city, but with few sights. The Costanera along the river is really nice, and there is a beach from which to swim. Buses are on a smart card, and 6 peso is the regular fare for cash. Drivers can overcharge, so beware.
Posadas has a very, very nice bus station, for anyone who happens to be wondering. Here’s where you need to go if you’re looking to spend the night there: there’s a closed off waiting room that’s open 24 hours near the place where the buses leave. You can smoke, watch cable TV, sleep on the benches – hell you can even set up your tent if you want. And the whole place has WiFi. It’s easily the best bus station I’ve ever seen – and I’ve slept in a lot of bus stations in a lot of countries. Not proven, but you could probably sleep the night on the beach by the river, perhaps camp. It is a safe neighbourhood.
As of December 2013, there's a lot of road constructions going on the roads around Posadas, especially at the intersection with and on the Ruta 105 and Ruta 12, if considering hitchhiking towards Santo Tomé. Traffic drives relatively slow at this places, but space to stop is scarce.
East towards Puerto Iguazu
Take yellow city bus #1 to transfer station then to Candeleria which lies 20 km away. There is a intersection and also a petrol station. Plenty of local city buses head out to the intersection. Cars go very slow past here with current construction. Hold a sign for Iguazu, helps to be specific. Dont take an intermediate destination as the highway north is fast, so hard to hitch onwards.
West towards Corrientes
From center take city bus #27 until it intersects with the 12. Lots of room for cars to pull over and ther is a Gendarmeria stop another 5-10km further if you can get to that then a ride the rest of the way should be easy.
North towards Encarnacion and Paraguay
From the centre, it should be about a 20 minute walks towards the Puente Internacional. Lots of crappy shops and a choripan place to spend the last of your fairly worthless pesos. Busy crossing. No bag searches or heavy questioning. You can not walk across the bridge, but it is easy enough to sneak on the public buses that cross. Tell them you lost your ticket if they enquire. On the Paraguay side, specify you are there for more than a day. Again, you can sneak on the public bus. This will take you past the bus station, public plaza and then further north. When it turns West, get off and follow the main route north towards Asuncion. Pain in the arse to hitch out.