Texans have not written just one constitution, but seven.
Here is a quick chronological outline of them, and a link to the corresponding entry on the Handbook of Texas Online website, an excellent resource on important people, places, dates and things in Texas history provided by the Texas State Historical Society.
Two constitutions were in effect before Texas was a member of the United States:
why did texans have to write a new constitution in 1845
Mexican constitution
Because the Texans were apart of the Spanish. The Spanish owned Texas. :D
Santa Anna didn't enforce the Mexican Constitution of 1824. That Constitution Texas supported. So of course, it angered Texans and tensions grew between Texans and the Mexican government and finally after all options failed, Texans resorted to war.
Texans did NOT write the Declaration of Independence. Texas did not exist in 1776 when Jefferson wrote it. Texas had nothing to do with the Declaration.
Texas did NOT support the 1824 Mexican constitution. That is why they declared their independence on March 2, 1836.
write the constitution
to write a colonial constitution
Because they liked relying on the national government to make decisions for them. :)
The Constitution was written in 1781.
Chinese
They needed a constitution to become a state.