Sports betting and online sports betting are not the same things in legal terms. Some states actively choose not to regulate sports betting but as a result, offshore sportsbooks are still an option to those residents and not explicitly illegal.
Many people assume that because gambling in some states is not permitted that it is impossible to wager on your favorite sport.
Please check with your local state laws or website for the latest information. Note that this is not professional legal advice and a compilation of online information only.