Can I use my CBI passport to enter the US?

Yes, but you will need a valid US visa unless your passport is from a country participating in the US Visa Waiver Program (which no Caribbean CBI nation currently does).

Will immigration officers ask why I have this passport?

It is rare, but if they do, keep it simple: state that you are a legal citizen of that country. Do not offer information about the investment process unless directly asked.

Is it better to carry both passports?

Keep your other passport stored securely in your accommodation's safe. Only carry the passport you are using for your current transit.

Traveling Through the Caribbean with a Citizenship-by-Investment Passport

Traveling with a Caribbean CBI passport functions exactly like traveling with any other passport from that nation. You must use your CBI passport for all entry and exit stamps in the Caribbean to maintain visa-free status and avoid legal discrepancies at borders.

Standardize your travel documents. Never mix passports when crossing a single border. Always use your CBI passport for the entire journey, including booking flights and checking into hotels, to ensure your name and document number match exactly.
Understand CARICOM movement. If you hold a passport from a CARICOM member state (like St. Kitts or Dominica), you are often entitled to the CARICOM Skilled Nationals regime. Research the CSME (CARICOM Single Market and Economy) framework to see if you qualify for extended stay or work rights beyond a standard tourist visa.
Manage dual-citizenship entry. When departing your country of residence, use your primary passport to leave. Upon arrival in the Caribbean, present only your CBI passport. Do not show both unless explicitly asked by an immigration officer.
Check regional visa reciprocity. Even within the Caribbean, visa-free access depends on which country issued your passport. Check the official immigration portal for the specific island you are visiting, as rules differ for OECS (Organization of Eastern Caribbean States) members versus others.

Can I use my CBI passport to enter the US?: Yes, but you will need a valid US visa unless your passport is from a country participating in the US Visa Waiver Program (which no Caribbean CBI nation currently does).
Will immigration officers ask why I have this passport?: It is rare, but if they do, keep it simple: state that you are a legal citizen of that country. Do not offer information about the investment process unless directly asked.
Is it better to carry both passports?: Keep your other passport stored securely in your accommodation's safe. Only carry the passport you are using for your current transit.