Prior to MAP-21, each apportioned program had its own formula for distribution, and the total amount of Federal assistance a State received was the sum of the amounts it received for each program. MAP-21 instead provides a total apportionment for each State and then divides that apportionment amount
among individual apportioned programs.

MAP-21 authorizes a total combined amount ($37.5 billion in FY13 and $37.8 billion in FY14 and FY 15) in contract authority to fund five formula programs (including certain set-asides within the programs described below):

• National Highway Performance Program (NHPP);
• Surface Transportation Program (STP);
• Highway Safety Improvement Program (HSIP);
• Congestion Mitigation and Air Quality Improvement Program (CMAQ); and
• Metropolitan Planning Program.

Figure 1 illustrates the distribution of funds across programs under MAP-21.

Figure 1: MAP-21 Program Apportionments

HSIP receives 7% of the States apportionment remaining after allocations to CMAQ and Metropolitan Planning, which amounts to approximately $2.4 billion each year, nearly double the amount apportioned to HSIP under SAFETEA-LU. The following sums are set-aside from the State's HSIP apportionment:

• Railway-highway crossings – $220 million;
• A proportionate share of funds for the State's Transportation Alternatives (TA) program; and
• 2% for State Planning and Research (SPR).

In addition, if the High Risk Rural Roads Special rule applies to a State, then in the next fiscal year the State must obligate an amount at least equal to 200% of its FY 2009 HRRR set-aside for high risk rural roads.

The final HSIP apportionment represents the amount of funding available to States for the advancement of highway safety improvement projects.