Upvote:5
It may depend on the visa restriction you may have, but usually you may enter and exit as many time you want.
But visa is not a guarantee you can enter in US: the immigration officer should still check if you have intention to overstay/work/etc. (in a way not permitted by your visa).
But it seems that your case is just tourism travel (and from nearby countries), and on short time (if you enter every 6 months, just few days after exiting US... this will rise a red flag). So I see no problems (if you have money to sustain you, and you are genuinely making tourism). OTOH I have no crystal ball and nobody could predict decision of the immigration officers.