Final answer:
Mexico struggled to maintain control over Texas due to a large influx of American settlers who resisted Mexican laws and culture, particularly the abolition of slavery, and who strongly desired Texas to become a U.S. state, culminating in the Texas Revolution and the Mexican-American War.
Step-by-step explanation:
The factors that most likely influenced Mexico's inability to maintain control over Texas for many years include the large influx of American settlers, the settlers' desire to expand slavery, and the inherent cultural and legal conflicts. In 1829, Mexico's abolition of slavery was specifically targeted to weaken the American settlers' position, as they largely came from slave states and brought with them enslaved people to work on the cotton plantations.
Despite Mexican efforts to integrate Americans through measures such as acculturation laws and strengthening military presence, the measures failed and actually exacerbated tensions. The American settlers in Texas proved resistant to Mexican laws and cultural assimilation, maintaining their distinct identity and continuously pushing for Texas to join the United States.
Moreover, the American expansionists saw annexation of Texas as part of their destiny and a continuation of the westward expansion endorsed by the concept of Manifest Destiny. Eventually, disputes over issues such as slavery and land rights contributed to the Texas Revolution and ultimately the Mexican-American War, which reshaped the boundaries and destinies of both nations.