More crude oil was spilled in U.S. rail incidents last year than was spilled in the nearly four decades since the federal government began collecting data on such spills, an analysis of the data shows.

Including major derailments in Alabama and North Dakota, more than 1.15 million gallons of crude oil was spilled from rail cars in 2013, according to data from the Pipeline and Hazardous Materials Safety Administration.

By comparison, from 1975 to 2012, U.S. railroads spilled a combined 800,000 gallons of crude oil. The spike underscores new concerns about the safety of such shipments as rail has become the preferred mode for oil producers amid a North American energy boom.

The federal data do not include incidents in Canada where oil spilled from trains. Canadian authorities estimate that more than 1.5 million gallons of crude oil spilled in Lac-Megantic, Quebec, on July 6, when a runaway train derailed and exploded, killing 47 people. The cargo originated in North Dakota.

Nearly 750,000 gallons of crude oil spilled from a train on Nov. 8 near Aliceville, Ala. The train originated in North Dakota and caught fire after it derailed in a swampy area. No one was injured or killed.

The Pipeline and Hazardous Materials Safety Administration doesn’t yet have spill data from a Dec. 30 derailment near Casselton, N.D. But the National Transportation Safety Board, which is the lead investigator in that incident, estimates that more than 400,000 gallons of crude oil were spilled there. Though no one was injured or killed, the intense fire forced most of Casselton’s 2,400 residents to evacuate in subzero temperatures.

The Association of American Railroads, an industry group, estimates that railroads shipped 400,000 carloads of crude oil last year. That’s more than 11.5 billion gallons, with one tank car holding roughly 28,800 gallons.

Last year’s total spills of 1.15 million gallons means that 99.99 percent of shipments arrived without incident, close to the safety record the industry and its regulators claim about hazardous materials shipments by rail.

But until just a few years ago, railroads weren’t carrying crude oil in 80- to 100-car trains. In eight of the years between 1975 and 2009, railroads reported no spills of crude oil. In five of those years, they reported spills of one gallon or less.

In 2010, railroads reported spilling about 5,000 gallons of crude oil, according to federal data. They spilled fewer than 4,000 gallons each year in 2011 and 2012. But excluding the Alabama and North Dakota derailments, more than 11,000 gallons of crude oil spilled from trains last year.

Last week, the principal Washington regulators of crude oil shipments by rail met with railroad and oil industry representatives to discuss making changes to how crude is shipped by rail, from tank car design to operating speed to appropriate routing. Transportation Secretary Anthony Foxx called the meeting productive and said the group would take a comprehensive approach to improving the safety of crude-oil trains.

Foxx said the changes would be announced within the next 30 days.