CHESTER, Vt. — Almost two decades after the National Trust for Historic Preservation put the entire state of Vermont on its list of endangered sites, citing big-box developments as a threat to its signature greenness, towns like this one are now sizing up a new interloper: the chain dollar store.

While Wal-Mart has managed to open only four stores in Vermont and Target still has none, more than two dozen Dollar General, Dollar Tree and Family Dollar stores have cropped up around the state. All three companies are thriving in the bad economy — between them, they have more than 20,000 outlets nationwide, selling everything from dog treats to stain remover and jeans to pool toys. Their spread through Vermont, with its famously strict land-use laws, has caught chain-store opponents off guard.

Shawn Cunningham, a resident here in Chester who is fighting Dollar General’s plan to open down the street from the town common, said that since dollar stores tend to be much smaller than big-box stores, they are often not barred by local zoning rules meant to keep sprawl in check.