What makes Texas a formal region?

Formal region. It is characterized by a common human property, such as the presence of people who share a particular language, religion, nationality, political identity or culture, or by a common physical property, such as the presence of a particular type of climate, landform, or vegetation. Political entities such as counties, states, countries, and provinces are formal regions because they are defined by a common political identity. Other formal regions include climate regions (e. g., areas with a Mediterranean climate), landform regions (e. g., the Ridge and Valley and Piedmont regions of Pennsylvania), and economic regions (e. g., the wheat belt of Kansas, the citrus-growing areas of south Texas, and the irrigated farmlands of the Central Valley of California). Formal regions can be defined by measures of population, per capita income, ethnic background, crop production, population density and distribution, or industrial production, or by mapping physical characteristics such as temperature, rainfall, growing season, and average date of first and last frost.