The US and the UK uses a baseline dot as the decimal mark. Most other European countries use the comma. Here is a short piece on the history of this matter.
My question is: When did the use of the comma as the decimal mark become (largely) extinct in the US? I ask because I happened to come across this 1868 document (Maine Supreme Court ruling) where the comma was used, suggesting that it was still in some regular use in the US as late as 1868.