The 15 best places to work in the United States

Fortune has released its 18th annual "100 Best Companies to Work For" and Google is once again atop the list.

Fortune partnered with the Great Place To Work Institute to distribute an employee satisfaction survey across corporate America asking questions about management, office culture, benefits, and hiring practices.

Here are the top 15 companies with the happiest employees:

1. Google

The tech giant from Mountain View, California holds the top spot for the sixth straight year due to its long list of perks, including a newly enhanced paternity leave program.

Last year: #1

2. The Boston Consulting Group

Fortune praises Boston's elite consultancy for its Social Leave of Absence program, which allows employees to take up to a year to pursue social-impact work somewhere around the world while developing expertise that benefits their career.

Last year: #3

3. ACUITY

The Sheboygan, Wisconsin insurance company made its debut on Fortune's list at a top spot for its recent focus on benefits like unlimited tuition reimbursement and an 8% contribution to employees' 401k plans.

Last year: N/A

4. SAS Institute

Fortune has regularly praised the analytics company from Cary, North Carolina for its focus on every employee, which includes full benefits given to the campus' land contractors.

Last year: #2

5. Robert W. Baird

Paul Purcell, CEO of the Milwaukee-based wealth management company, has one rule: "no assholes here" - and actually fires employees for breaking it.

Last year: #9

6. Edward Jones

This large investment services firm headquartered in St. Louis is one of the few remaining private partnerships on Wall Street and boasts an "industry low turnover rate of 8%."

Last year: #4

7. Wegmans Food Markets

Consumer Reports rates the Rochester, New York-based supermarket chain the best grocery store in America, and Fortune credits its culture for compelling its employees to excel at their jobs.

Last year: #12

8. Salesforce

The cloud computing giant in San Francisco has grown twofold over the past few years largely due to its "fun-laden events" like an Oktoberfest-themed 'Bring a Referral' happy hour with plane tickets as a reward for a successful referral, according to Fortune.

Last year: #7

9. Genentech

The biotech company headquartered in South San Francisco is proud of its diversity initiatives, which include developing female leadership.

Last year: #6

10. Camden Property Trust

Fortune says that the office culture of the Houston-based real estate trust is not only fun but the company also "takes care of employees' families with fully furnished vacation suites, [a] 20% discount on rent, and college scholarships."

Last year: #11

11. Kimpton Hotels & Restaurants

Employees at this hospitality group based in San Francisco are encouraged to strive for leadership through mentorship programs to keep the company growing.

Last year: #21

12. Quicken Loans

The mortgage company is dedicated to revitalizing its home city of Detroit, and employees get to enjoy a company box at Lions games.

Last year: #5

13. Riot Games

Riot Games is the Santa Monica-based developer behind the best-selling video game "League of Legends" and has video game tournaments with its South Korean offices.

Last year: N/A

14. David Weekley Homes

After 10 years at the Houston real estate developer, employees have the chance to go on a four-week paid sabbatical as well as the option of a two-week unpaid extension with an extra $2,000 for expenses.

Last year: #13

15. Burns & McDonnell

Fortune says that this Kansas City, Missouri-based, employee-owned engineering firm "boasts one of the best stock-ownership plans in the nation," according to Fortune.

Last year: #14

You can check out the full list at Fortune's website.