Mile Markers on U.S. 281 North of Downtown San Antonio

[ethanhopkin14]

Please help me.  I remember U.S. 281 between I-35 and I-410 on the north side of San Antonio having mile markers.  I kinda remember them being extensions of I-37's mile markers.  I have looked for years and can't seem to find them anymore.  Maybe I don't see them because of how dangerous this section of 281 is.  Does anyone else remember this or have any info on this?