Blocks and Sections — How Texas Railroad Surveys Grid the Land

In West Texas — the Permian Basin, the Trans-Pecos, and the Panhandle — most TXSS legal descriptions take the form Block N, Section N, Railroad Survey, County. This is the Block & Section convention, and it is the closest thing TXSS has to a regular grid. It looks superficially like the PLSS township–section grid, but it is anchored in 19th-century railroad land grants rather than principal meridians and baselines.

This article explains where Block & Section came from, who the major railroad surveys are, how to read the notation, and how to disambiguate references when the same block number appears in multiple surveys.

Where Block & Section Came From

After Texas joined the Union, the state owned millions of acres of public land — much of it in the Trans-Pecos and the Panhandle, far from existing settlement. In the 1850s–1880s, Texas issued large land grants to railroad companies as inducements to build track across the state.

The deal was simple: build a railroad through Texas, get the land along it. The grants were enormous — sometimes tens of thousands of acres per mile of track — and the railroad companies surveyed their grants into blocks and sections so they could sell parcels to settlers.

The grants overlapped less than you might expect — each major railroad got a particular corridor — but they did overlap in places, which is why block numbers alone can be ambiguous (Block 5 might exist in both the T&P and the GC&SF surveys, and you need the survey name to disambiguate).

What "Block" and "Section" Mean Here

In Block & Section TXSS:

• A block is a large rectangular area of a railroad land grant. Blocks are numbered within each railroad survey (Block 1, Block 2, ... up to the highest assigned number for that survey).
• A section is a one-square-mile subdivision within a block — usually ~640 acres, similar to PLSS sections but not always exactly that size.
• A survey here means the named railroad's overall grant — for example, "T&P Survey" refers to the Texas and Pacific Railway Company Survey, the railroad's full land grant.

Critically, block numbers are scoped to each railroad survey. There is no statewide Block 5; there are many Block 5s, one in each survey that has one. The full unambiguous reference is:

(County, Survey Name, Block, Section)

A Typical Block & Section Reference

Block 5, Sec 14, T&P Survey, Reeves County
Blk 13 Sec 9 H&TC Survey, Loving County
Block 5, T&P RR Co. Survey, Section 14, Reeves

All three formats are equivalent. Township America's parser is tolerant of word order, abbreviations, and punctuation.

The reference identifies a one-square-mile section within Block 5 of the T&P railroad grant, located in Reeves County.

The Major Railroad Surveys

Several dozen railroads received Texas land grants. These are the ones you will see most often in modern Block & Section descriptions:

The T&P and GC&SF surveys are the dominant ones in the Permian Basin. The H&TC has the broadest geographic spread because it was an early grant.

Abbreviation Variants

Railroad survey names appear in many forms across deeds, RRC filings, and lease databases:

• T&P / T & P / T.&P. / T&P RR Co. / T&P Ry. Co. / Texas and Pacific / Texas and Pacific Railway Company
• H&TC / H&TC RR / Houston & Texas Central / Houston and Texas Central Railway Company
• GC&SF / Gulf, Colo. & Santa Fe / Gulf, Colorado and Santa Fe Railway Company

Township America's parser normalizes all variants to a canonical survey name. The response includes a survey_name_norm field with the canonical form, so downstream code can join on a consistent name regardless of how the source data abbreviated it.

Where Block & Section Dominates

Block & Section is the dominant TXSS convention in three major regions of Texas:

Permian Basin (West Texas)

The heart of US oil production. Counties like Reeves, Loving, Ward, Winkler, Pecos, Ector, Midland, Crane, Andrews, Martin, and Howard are predominantly Block & Section under the T&P, GC&SF, and H&TC railroad surveys.

This is where most landmen, lease analysts, and operators encounter TXSS — and where the Block & Section convention shows up in drilling permits, well headers, lease maps, and pipeline rights-of-way.

Trans-Pecos (Far West Texas)

Counties like El Paso, Hudspeth, Culberson, Jeff Davis, Presidio, and Brewster. Block & Section dominates here under GC&SF, T&P, and H&TC grants, with some smaller railroad and state surveys interspersed.

Texas Panhandle

Counties like Dallam, Hartley, Moore, Sherman, Hansford, Ochiltree, Lipscomb, Hemphill, Wheeler, and beyond. The H&GN (Houston and Great Northern) and several other surveys appear alongside T&P and H&TC.

How to Read a Block & Section Reference

A complete Block & Section reference has four required pieces:

1. County — e.g., Reeves County, Loving County
2. Survey name — e.g., T&P, H&TC (sometimes called "Original Grantee" or "Granted To")
3. Block number — e.g., Block 5, Blk 13
4. Section number — e.g., Sec 14, Section 9

Sometimes you will see the survey name written as the abstract record's "Grantee" field rather than as a survey name explicitly. For example:

Section 14, Block 5, T&P RR Co., Reeves County, Abstract 1234

Here the railroad company name (T&P RR Co.) functions as the survey identifier, and the abstract number ties the section back to GLO's index.

Disambiguating When the Survey Name Is Missing

If you have a description like Block 5, Sec 14, Reeves County with no survey name, you need to know:

• How many surveys in this county have a Block 5? If only one, the reference is unambiguous and the converter returns that section. If multiple, you have a real ambiguity.

Township America's resolver handles this as follows: it queries (county, block, section) first; if it resolves to exactly one row, it returns the match. If it resolves to multiple, the API returns a 422 with a list of candidate (abstract, survey, section) tuples so the caller can pick.

In practice, most West Texas references include the survey name explicitly because everyone working in the region knows ambiguity is common.

Sections and Acreage

In theory, a Block & Section parcel is one square mile (640 acres), like a PLSS section. In practice:

• Block boundaries were laid out by 19th-century surveyors using chain and compass, often in harsh terrain. Some blocks are slightly larger or smaller than the nominal grid.
• Sections at the edge of a block absorb the variance — exactly like PLSS sections at the north and west edges of a township absorb meridian convergence.
• Survey errors or terrain irregularities sometimes produce fractional sections that are notably smaller or larger than 640 acres.

When Township America returns a section polygon, the computed acreage reflects the actual polygon — not the nominal 640.

How Block & Section Differs from PLSS Townships

For PLSS users, the Block & Section convention can feel familiar, but the analogy is partial:

The conceptual difference: PLSS is a single national grid with regional meridians. Block & Section is many parallel grids, one per railroad survey, often overlapping geographically. You cannot read a Block & Section reference without knowing which railroad's grid it lives in.

Converting a Block & Section Reference

Township America's converter accepts Block & Section references in any of the supported formats. The most reliable form includes all four pieces:

Block 5, Sec 14, T&P Survey, Reeves County

For shorthand or partial references, the converter will try to disambiguate; if the block number is unique within the county, you do not need to include the survey name. If it is not unique, the API will return candidate matches.

For batch workflows, see Convert Texas Abstract to GPS Coordinates — the same workflow handles Block & Section descriptions.

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