The "most reliable" source depends entirely on where the development is located and what stage the project is in (e.g., a confirmed legal reality vs. a likely rumor).

For a professional or legal library, the only 100% reliable sources are the government planning agendas.

1. The "Gold Standard" (For Confirmed, Legal Plans)

If you are tracking development for business operations, you must distinguish between the City of Las Vegas and Clark County. The "Las Vegas Strip" is located in unincorporated Clark County, not the City of Las Vegas.


2. The Best News & Industry Intelligence (For Context & Trends)

Government documents are accurate but dry. Use these sources to understand the "who" and "why" behind the projects.

Summary Recommendation Table

If you need... Go to...
Legal/Zoning Certainty Clark County Comprehensive Planning (for Strip) or City of LV Planning (for Downtown)
Early Rumors / Scoops Vital Vegas (Twitter/Blog)
Market Analysis Las Vegas Review-Journal or UNLV CBER
Construction Data Nevada Contractors Association

Sources

https://www.clarkcountynv.gov/government/departments/comprehensive_planning_department/library/major-projects

https://www.clarkcountynv.gov/government/departments/comprehensive_planning_department/special-projects#:~:text=Parks %26 Recreation Master Plan,Corridor Transit Oriented Development Plan

https://www.clarkcountynv.gov/government/departments/comprehensive_planning_department/special-projects

https://www.lasvegasnevada.gov/Business/Planning-Zoning/Master-Special-Area-Plans-Archive