4 Tex. Admin. Code § 41.20
Quarantined areas are as follows for Starr County. Beginning at a point where U.S. Highway 83 intersects the Zapata-Starr County line and following U.S. Highway 83 in a southeasterly direction to the south fence of the M. Ramirez Pasture at the north city limits of Roma, approximately 17 miles; thence, following the south fence of the M. Ramirez Pasture in a northeasterly direction to where it intersects the west fence of the G. Madrigal Ranch, approximately .4 mile; thence, following the meanderings of the west fence of the G. Madrigal Ranch in a southeasterly direction, around the east side of the R. Pena addition to the City of Roma to a dirt road, approximately .9 mile; thence, following the same dirt road in a southerly direction to where it intersects U.S. Highway 83 at the Roma Graveyard, approximately .3 mile; thence, following the north side of D.S. Highway 83 in an easterly direction through Rio Grande City to its intersection with Loop 83, approximately 18 miles; thence, following the north side of Loop 83 in an easterly direction to its intersection with the MP Railroad right-of-way, approximately 3.5 miles; thence, following the north side of MP Railroad in an easterly direction to the Starr-Hidalgo County Line, approximately 13 miles.
4 Tex. Admin. Code § 41.20