Horgos-Röszke border crossing
The crossing is situated on the E75, which is a motorway to Budapest and an express carriageway to Novi Sad. According to a local, the direction of traffic is dependent on the season. Walking across this border is not permitted on the motorway, but it seems tolerated as long as you can stand being berated.
It is advisable to cross on foot if the queue is too long, but waiting in the car can be worth it if your driver allows it since it is quite a walk between the posts.
On Hungarian side walk for 300 meters and you will find a petrol station where you can ask drivers. Be aware that most of the cars are Serbian drivers going somewhere nearby, so it is not that easy to get away, but you will not starve there either.
Whether you can hitch from the border depends on the mood of the police that day. Sometimes there's no problem with standing a few meters down from passport control, and you might even see other hitchhikers. At other times, the police may ask you to move to the petrol station 1.5 km down the road. However, if they ask you to move, it often suffices to walk another 200 m down to the green road sign and hitch from there.
There's, however, a big parking lot with insurance and customs agents' booths right after you walk out of the control booths - a lot of people stop here to get some fresh air, get their paperwork in order or to take a leak. This is a perfect chance to talk to people and score direct rides into Bulgaria and even deep into Turkey! Look for out-of-place plates such as UK, Austria, Germany or Netherlands - these are almost exclusively Bulgarian and Turkish expatriates. A lot of opportunities here! The cops also can't kick you out of a parking lot - you're obviously getting insurance! This is especially true between May and August.
If you want to get a lift to southern Serbia, Macedonia or Bulgaria, it is best to write a sign "Bulgaria", because very many Bulgarians are driving back from Western Europe through this border crossing. Even if you are not going so far, you can rely on them to leave you at, for example, the big toll station after Beograd.
I walked across this border after a driver took me there (he was too cautious to take me across) and made some border guards angry by doing so, but it was fine afterwards. There was almost no traffic going into Serbia that day and people seemed wary to pick someone up that close to the guards. I walked down the highway a little bit and managed to stop a car while walking. I had a strange encounter between the borders with (presumably) a stuck and injured refugee. He asked me for water in Turkish and I gave my bottle to him, being watched closely by what seemed to be Serbian military police. Serbian and Turkish officers were waiting with a doctor at the other side of the border, joking and laughing together. - Rebew (talk) (Aug. 2022)