MdMUTCD R7-4(9) Bus Stop (Symbol) No Stopping Sign (Maryland Supplement to Manual on Uniform Traffic Control Devices)
Maryland, United States
Bus stop no standing / no parking any time regulatory sign

Standard sign book code R7-4(9); Maryland-specific variant of R7-4 regulatory sign from federal Manual on Uniform Traffic Control Devices standard
Maryland Manual on Uniform Traffic Control Devices Sign Book https://apps.roads.maryland.gov/businesswithsha/bizStdsSpecs/desManualStdPub/publicationsonline/oots/SignBook/pdf/R7-4(9).pdf
Maryland State Highway Association