do you need a passport to travel by air to California?

if am in texas and trying to go to california

yes and you will need a watch with crack in it

from where?

Yup.

Only if you're coming from somewhere outside the country.

no you are still within the united states

You only need a passport to travel outside the US, from within the US

NO you are still flying within the US, just buy your ticket and fly on.

Travel within the U.S. and its territories does not require a passport. However if you've already got one, might consider carrying it as it's a solid form of ID that nobody will argue with.

Nope. You are fine. Passport by definition is a document that you require to go from a port located one country to a port located in a different country. Since Texas and California are part of the same country, you do not require a passport. Still you will require a valid photo ID. Photo Driver's Licenses are commonly used.