“You don’t plop a small city into the middle of an agricultural district,” he said. Like most Amish and Mennonites in the area, Mr. Oberholtzer uses a horse-drawn buggy to go to church, attend the hay auction or run errands to town. He has not ruled out moving away if the development goes forward.

“Traffic is already a nightmare, and people who move into that development won’t know much about the Amish or be expecting buggies on the road,” he said.

Mr. Oberholtzer blames the county’s zoning regimen as the culprit more than the Hursts’ vision. Lancaster’s zoning is a patchwork of development and preservation districts. The Oregon Dairy is in an agricultural district, but the Hurst parcel is zoned for a mixed-use development like the one Mr. Hurst plans.

Donald Kraybill, a retired professor from nearby Elizabethtown College and a noted expert on Amish life, warned at a public hearing last year that some Amish and Mennonites might leave the area if the development went on as planned. Manheim Township, however, approved the development after years of sometimes contentious public hearings. Mr. Oberholtzer and two other residents are contesting the approval. But Mr. Hurst is confident the law is on his side.

The presence of thousands of Amish and Mennonites in the area makes Oregon Village’s contours different from a typical mixed-use rendering. The Amish and Mennonites have farmed in Lancaster County for centuries, but they started attracting the attention of tourists and outsiders only in the mid-1950s, when Amish and non-Amish lifestyles began to rapidly diverge. Since then, the area’s tourism industry, offering traditional treats like shoofly pies and buggy rides, has boomed.

Lancaster County is feeling the development squeeze from all sides. The westernmost exurbs of Philadelphia have been pressing into the farmland from the east, while the city of Lancaster, population 60,000, has been sprouting its own suburbs.