The annual March for Life, a protest against the Roe v. Wade Supreme Court decision on abortion rights, will draw thousands of demonstrators to the Mall on Monday. That will cause traffic congestion on nearby streets and add many more riders to Metrorail.

A noontime rally on Monday will precede the march. The rally will be on the Mall west of Eighth Street near the Smithsonian Castle. The march is set to begin at 1:30 p.m.

Smithsonian, on the Blue and Orange lines, is the nearest Metrorail station. But it is easily overwhelmed by big crowds for major rallies. Participants could also use L’Enfant Plaza and Federal Center SW to the south of the Mall, or Federal Triangle and Archives stations to the north. They all are farther from the rally site than Smithsonian.

The Capital Weather Gang’s forecast for Monday includes a chance of showers, with a high temperature in the mid-50s.

The march route is the usual one, going north to Constitution Avenue NW, then east to the Supreme Court Building on Capitol Hill. Police close the streets along the way until the marchers have passed. See a route map.

The effect on traffic is likely to be greatest after the events end about 5 p.m. or later, and the marchers on Capitol Hill disperse into the midst of the evening rush hour. Many participants will walk north to Union Station or south to the Capitol South Metro station.

Tips on transit riding

Rally participants planning to take transit to the Mall can use Metro’s online Trip Planner to check their bus and train options. Also useful is the Next Bus system, which can be used either by phone or Internet to predict the arrival time of buses at individual bus stops.

However, it’s likely that some Metrobus routes will be slowed or detoured because of street closings and crowding near the Mall and Capitol Hill, and that will affect the accuracy of both Trip Planner and Next Bus in those areas.

The afternoon events might also affect the arrival times for homeward- bound MTA commuter buses.

Parking fees will be in effect Monday at Metro’s lots and garages. At most of these, drivers need a Metro SmarTrip card to pay for parking, but 19 stations now accept major credit cards. See a list of those stations.

The plastic SmarTrip cards also can be used to pay for riding Metrorail or Metrobus, as well as on many suburban bus lines. Whether participants are using the plastic cards or the paper Farecards, it’s always best to load up the value of a roundtrip, to avoid waiting in long lines at the fare vending machines after the march.