Largest employers in Houston and Tampa

So I'm thinking hard about where I should be looking for work. My basic list looks something like this:

• NASA
• University of Houston (Main, Downtown & Sugarland)
• City of Houston
• Harris County
• Hewlett Packard
• Veterans Administration
• Internal Revenue Service
• Houston Community College
• Lone Star College
• Rice University

But then I thought about who are the biggest employers in Houston. And because the Internet is so nifty, I found a list on a website called Here Is Houston. Here's their top ten:

1. Memorial Hermann Health System
2. The University of Texas MD Anderson
3. United Airlines
4. The Methodist Hospital System
5. Exxon Mobil Corporation
6. UTMB Health
7. Kroger Company
8. Shell Oil Company
9. National Oilwell Varco
10. Schlumberger Limited

Kroger surprised me.

Wikipedia also lists "Companies with a large presence in Houston:"

Although Exxon Mobil has its corporate headquarters in Irving, Texas, most of its employees are in Houston. Hewlett-Packard maintains a large presence in Harris County. The corporate offices of Imperial Sugar and Minute Maid, a regional headquarters for Unocal 76, and an office of Schlumberger, are based in nearby Sugar Land, Texas. CB&I and US Oncology are based in The Woodlands.

So since I was looking at that, I was curious about who the largest employers in Tampa are. I found it at Sun Coast Employers:

1. School District of Hillsborough County
2. HCA
3. Publix Supermarkets
4. Pinellas County School District
5. MacDill Airforce Base

So I work at an employer in the top five.