I guess I'd quibble somewhat with the aforesaid... Here in the western U.S., there are large, commercial potato farms nearby where we can go to buy them directly. (We do grow some of our own... a different variety than available commercially).
They are placed in what we call 'gunny sacks'... fairly large burlap bags. The potatoes are only 'field clean'... they haven't been washed thoroughly. We take them home as is and put them in the basement. They keep best, according to the potatoe people, at 45 to 50 degrees F with only moderate humidity. Ours keep all winter.
The key is temperature and ventilation... never store them in plastic or airtight containers...