There are no laws (federal or state) that mandate that employees give preference in their hiring to American workers. 
 

The Hire America program is an attempt by the Trump Administration to encourage the hiring of more Americans rather than giving preference to foreign workers.

As of today the program is rolled out in an Executive Order which gives guidance to Federal agencies on specific actions they must take.

The intent is to create an economic environment that generates higher wages and higher employment for American workers.

 

To that end, agencies, (such as the State Department, Homeland Security, Justice Department  and Department of Labor) are directed to rigorously enforce and administer the laws governing entry into the United States of workers from abroad.

 

The Secretary of State, the Attorney General, the Secretary of Labor, and the Secretary of Homeland Security, were directed to propose new rules and issue new guidance, to supersede or revise previous rules and guidance if appropriate, to protect the interests of United States workers.

The aim is to prevent fraud and abuse of the immigration system governing foreign workers.  The President would like to see that H-1B visas are awarded to the most-skilled or highest-paid petition beneficiaries.

You can read the full Executive Order [Buy American/Hire American].