US Currency is .0043 inches thick that means that 100 bills is .43 inches thick.
A traveler must declare that they are carrying $10,000 US or more so $9,999 is the limit if that is your view.
There is actually no limit to the amount you are carrying as long as you report amounts of $10,000 US or more.
You can carry a trillion dollars as long as you can demonstrate where you got the money.
Cash in any currency and any thing freely negotiable counts $5000 cash and $6,000 in travelers check count and $11,000.
If you have $3,000 US cash and a check in someone?s or a company name for $15,000 means that you only have $3000 for purposes of the requirement to declare.
Entering Canada it is $10,000CA. The exchange rate used for foreign currency is the noon fixing by the Bank of Canada for yesterday. (On Monday the Friday NOON fixing used. If yesterday was a holiday then the previous fixing is used. In RD it is $10,000US
If you are trying to follow the rules, you have to understand the rules.
To answer the original question, I use a money belt.
DS