Coach Joachim Löw had joined in the Schalke captain's mourning before the game, saying that the crash "makes me sad and desperately hurt".
A minute of silence was also held before kickoff, and the German team were wearing black ribbons in memory of the crash victims.
But it was Höwedes' display of the sign, reading simply "Haltern mourns" with the coat of arms of his home town, while singing the national anthem which most affected spectators in the stadium and watching at home on television.
"Everone knows I come from Haltern am See and still have many friends and relatives there today," he tweeted on Tuesday.
"I'm indescribably sad about the terrible accident and wish all families and loved ones the strength to get through this."
Aussies hold Germans to draw
Lukas Podolski saved Germany's blushes with an equaliser nine minutes from time in an international friendly against Australia in Kaiserslautern on Wednesday night.
“I get the feeling, some people really want to write him off. But I know that Lukas can always find encouragement, he can always find a goal. It was his 48th goal for Germany. That number speaks for itself,” said national coach Joachim Löw after the match.
Australia had taken a 2-1 lead thanks to Troisi's first-half header and a free-kick from captain Mile Jedinak which cancelled out Marco Reus's early goal.
Having shocked the world champions 2-1 in Moenchengladbach four years ago, an inexperienced Australian side came close to producing another upset as the hosts' post-World Cup hangover continued.
The match was a warm up for Germany's European Championships qualification game aginst Georgia on Sunday in Tbilisi.
“It was a good test, we can take a few lessons from it. The team will raise its level again against Georgia," said Löw.
Australia were impressive in their first international since winning January's Asian Cup in Sydney and Troisi said the fact they were disappointed not to beat the world champions showed that the Socceroos are on the rise.
Australia's James Troisi said the Socceroos' 2-2 draw with Germany showed just how far the Asian champions have come in 12 months."
Few would have thought 12 months ago that we would nearly beat the world champions - I surely wouldn't have - but it shows how far we have come as a team," said the 26-year-old.
"I think Germany didn't expect us to play like we played and to put them under so much pressure. They weren't comfortable at all.
"We are pleased with our performance, but we missed some chances - we could have had three or four more.
"A draw is ok, but it's great to see how well we play against the best.
"We really wanted to put on a good show for people back home who woke up early to watch us play."
The Socceroos now face Macedonia on Monday in their last European friendly and captain Jedinak hopes their stunning display against the world champions will have won them a few more fans back home.
"I think this can take our belief to the next level. I think everybody, if they didn't believe, now they will," said the 30-year-old Crystal Palace midfielder.
Police said Friday five incidents involving so-called scary clowns had occurred in two north German town, including one assailant who hit a man with a baseball bat, amid fears that Halloween could spark a rash of similar attacks.
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