Yeah, you can call them and be told...they don't know.The County employees are not responsible for tracking down jail records...unless they want to charge you to determine that.So, unless you have the time and free phone charges, don't bother.Jail records are usually disposed after a certain time-frame.Court records however might be available...depending on many factors (below).
The local newspaper... probably will not have any information posted unless your G-GM was convicted of a less than felony offense.The size of the town/county would also be a factor.Back in 1930, newspapers didn't usually post every action taken by the local law enforcement.
If you had identified the name of your G-GM (and KNOW it was her versus someone having the same name, or someone using her's), it would help to identify further information about the date of enumeration, etc.Also, in many cases, the person is enumerated in "jail." but also at their normal residence.This indicates the person may have only been in jail for a short period of time, time for withdrawal of alcohol or drugs, time to investigate IF the person had even committed a crime, and in some cases to protect them from other persons.
There might be a period of time between this enumeration and back dated to an arrest. Their being in jail does not mean they had been convicted of any crime, they could have been just arrested, being held for later court action, or for questioning/investigation. Or, if the arrest was simple alcohol related, there might not have been anything more than being held overnight and put back on their way. Transients are often held then booted out of town.
The newspaper may have a short item, but chances are you would waste a lot of time in reviewing those microfilms.The County Jail "might" have also been contracted to hold city detainees.Misdemeanor arrests are often uncharged, or even after charging, these records usually "disappeared."
I have 32 years of federal law enforcement experience.I also now do background investigations for security clearances.I OFTEN find I can not obtain information on local misdemeanor arrests even back two to three years.Even the local courts don't keep them.
HOWEVER, County Superior Courts in most jurisdications across the country are required to maintain court records.In this case...IF she was arrested, charged and appeared in court to answer the charges, there "might" be a record...unless the charge was ultimately dropped to a petty offense or minor misdemeanor.THEN the record might have been expunged after a year or two of law abiding actions of the defendents.IF you do not live in that area, then a local person (or contact the Superior Court Clerks...they would probably charge to check the names), might research.BUT, in either case, you might have to pay for the review of records.
So, you can do the research and might find some answer...or more questions.Or, you can note that facts indicate that G-GM might have been in jail on the day of enumeration.Personally, if a male, I'd suspect drunk and disorderly.If a female, family related or fraud (checks, taking of funds, etc).Her age at the time would also be an indicator.