Amtrak CEO Joe Boardman said the increase in ridership was evidence of its rail service.
"Amtrak is delivering record ridership across the country and serving as an economic engine to help local communities grow and prosper," Boardman said in a statement.
Amtrak noted that the biggest growth areas in its ridership in recent months have come on state-supported shorter routes where the company signs deals with state governments to pay for rail service.
The state-supported routes, which are less than 750 miles, saw a ridership increase of 6.8 percent from July 2012 to July 2013. The shorter routes carried 1.46 million passengers last month, compared to 1.37 million in July 2012.
Amtrak's popular northeast regional and Acela high-speed trains carried 964,608 passengers in July 2013, compared to 939,602 in the same month last year.
The ridership jump is likely to buoy Amtrak supporters as they gird for an expected fight in Congress over federal funding for the rail company this fall.
The bill that authorizes Amtrak's funding, the Passenger Rail Investment and Improvement Act (PRIIA), is scheduled to expire in September.
Amtrak has traditionally received about $1 billion per year from Congress since its inception in 1971.
Republicans in the House have already attempted to cut the agency's funding by 21 percent this year in a broad Transportation and Housing bill that was pulled from the floor before lawmakers left Washington for their traditional August recess.
Democrats have argued that Amtrak's recent ridership increases show that Congress should be increasing the amount of money it gives to Congress instead of attempting to cut it.
-This story was updated at 3:50 p.m. to correct an earlier version that misidentified the number of years that have passed since Amtrak's founding.