What era is this JC Higgins 24" bike?
1949 - 1950 JC Higgins built by Murray.  The serial number is stamped into the bottom bracket.  Time and rust will make it difficult to read.  Keep scrubbing.  MOS is the prefix for Murray of Ohio for Sears.  L, M, N, O, P will indicate the year.

This bike is missing the tank.



Here's a picture of one complete with tank and rear rack. Some models had painted tanks rather than the exhaust ports. Some had painted rims, some had chrome rims